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ALSA buffer xrun induced by low quality source in ffmpeg capture
24 juin 2015, par Peter BecichI am attempting to transfer some old Video 8 tapes to my computer, though an EasyCap USB stick and the motherboard’s sound line-in, on Ubuntu. I believe the arguments are correctly laid out below to capture from two independent streams, and encode them both into the output MP4 file.
Edit :
I can simplify the question a bit, now.
ALSA buffer overrun (or underrun ?) is induced by the unreliable/noisy audio source. For instance, if ffmpeg captures the beginning of tape playback, this causes "buffer xrun" far beyond when the tape gets up to speed and playback should be normal.
It is interesting that the bitrate shown in the ffmpeg log shoots up higher than normal when it’s producing a garbage output ! (Is this bitrate a sum of of audio and video bitrates ?)
I’ve tried a couple of audio encoding codecs, and had the same problem.
Using
libfdk_aac:Metadata:
encoder : Lavf56.15.102
Stream #0:0: Video: h264 (libx264) ([33][0][0][0] / 0x0021), yuv422p, 640x480, q=-1--1, 29.97 fps, 11988 tbn, 29.97 tbc
Metadata:
encoder : Lavc56.13.100 libx264
Stream #0:1: Audio: aac (libfdk_aac) ([64][0][0][0] / 0x0040), 48000 Hz, mono, s16, 128 kb/s
Metadata:
encoder : Lavc56.13.100 libfdk_aac
Stream mapping:
Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (libx264))
Stream #1:0 -> #0:1 (pcm_s16le (native) -> aac (libfdk_aac))
[alsa @ 0x22038a0] ALSA buffer xrun. 0kB time=00:00:00.00 bitrate=N/A
[alsa @ 0x22038a0] ALSA buffer xrun.1934kB time=00:00:02.76 bitrate=5723.5kbits/s
[alsa @ 0x22038a0] ALSA buffer xrun.4795kB time=00:00:05.49 bitrate=7150.1kbits/s
[alsa @ 0x22038a0] ALSA buffer xrun.7668kB time=00:00:08.21 bitrate=7646.1kbits/s
[alsa @ 0x22038a0] ALSA buffer xrun.1475kB time=00:00:10.94 bitrate=8588.9kbits/s
[alsa @ 0x22038a0] ALSA buffer xrun.3822kB time=00:00:13.66 bitrate=8289.0kbits/s
[alsa @ 0x22038a0] ALSA buffer xrun.5388kB time=00:00:16.38 bitrate=7695.0kbits/s
[alsa @ 0x22038a0] ALSA buffer xrun.6896kB time=00:00:19.10 bitrate=7244.0kbits/s
[alsa @ 0x22038a0] ALSA buffer xrun.8980kB time=00:00:21.84 bitrate=7118.8kbits/s
[alsa @ 0x22038a0] ALSA buffer xrun.2032kB time=00:00:24.55 bitrate=7349.3kbits/s
[alsa @ 0x22038a0] ALSA buffer xrun.4612kB time=00:00:27.27 bitrate=7391.1kbits/s
[alsa @ 0x22038a0] ALSA buffer xrun.6660kB time=00:00:29.98 bitrate=7284.6kbits/s
[alsa @ 0x22038a0] ALSA buffer xrun.9123kB time=00:00:32.68 bitrate=7299.3kbits/s
[alsa @ 0x22038a0] ALSA buffer xrun.0641kB time=00:00:35.39 bitrate=7091.7kbits/s
[alsa @ 0x22038a0] ALSA buffer xrun.2601kB time=00:00:38.13 bitrate=7002.6kbits/s
[alsa @ 0x22038a0] ALSA buffer xrun.5828kB time=00:00:40.87 bitrate=7181.0kbits/s
[alsa @ 0x22038a0] ALSA buffer xrun.8481kB time=00:00:43.60 bitrate=7229.9kbits/s
[alsa @ 0x22038a0] ALSA buffer xrun.1461kB time=00:00:46.34 bitrate=7328.0kbits/s
[alsa @ 0x22038a0] ALSA buffer xrun.3982kB time=00:00:49.06 bitrate=7342.7kbits/s
[alsa @ 0x22038a0] ALSA buffer xrun.6565kB time=00:00:51.77 bitrate=7367.8kbits/s
[alsa @ 0x22038a0] ALSA buffer xrun.9718kB time=00:00:54.51 bitrate=7471.3kbits/s
[alsa @ 0x22038a0] ALSA buffer xrun.2341kB time=00:00:57.25 bitrate=7489.2kbits/s
^Cframe= 1760 fps= 29 q=-1.0 Lsize= 53946kB time=00:01:00.04 bitrate=7360.3kbits/s
video:53880kB audio:53kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.022994%
[libx264 @ 0x2217ac0] frame I:8 Avg QP:24.00 size: 55686
[libx264 @ 0x2217ac0] frame P:1752 Avg QP:27.66 size: 31237
[libx264 @ 0x2217ac0] mb I I16..4: 100.0% 0.0% 0.0%
[libx264 @ 0x2217ac0] mb P I16..4: 15.0% 0.0% 0.0% P16..4: 80.2% 0.0% 0.0% 0.0% 0.0% skip: 4.8%
[libx264 @ 0x2217ac0] coded y,uvDC,uvAC intra: 45.3% 86.6% 59.4% inter: 65.7% 81.3% 11.5%
[libx264 @ 0x2217ac0] i16 v,h,dc,p: 40% 25% 26% 9%
[libx264 @ 0x2217ac0] i8c dc,h,v,p: 45% 24% 19% 12%
[libx264 @ 0x2217ac0] kb/s:7516.07
Received signal 2: terminating.Using
libvorbis:Metadata:
encoder : Lavf56.15.102
Stream #0:0: Video: h264 (libx264) ([33][0][0][0] / 0x0021), yuv422p, 640x480, q=-1--1, 29.97 fps, 11988 tbn, 29.97 tbc
Metadata:
encoder : Lavc56.13.100 libx264
Stream #0:1: Audio: vorbis (libvorbis) ([221][0][0][0] / 0x00DD), 48000 Hz, mono, fltp, 128 kb/s
Metadata:
encoder : Lavc56.13.100 libvorbis
Stream mapping:
Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (libx264))
Stream #1:0 -> #0:1 (pcm_s16le (native) -> vorbis (libvorbis))
[alsa @ 0x1a948a0] ALSA buffer xrun. 0kB time=00:00:00.00 bitrate=N/A
[alsa @ 0x1a948a0] ALSA buffer xrun. 402kB time=00:00:04.37 bitrate= 752.3kbits/s
[alsa @ 0x1a948a0] ALSA buffer xrun.4122kB time=00:00:08.80 bitrate=3833.0kbits/s
[alsa @ 0x1a948a0] ALSA buffer xrun.8722kB time=00:00:13.14 bitrate=5436.3kbits/s
[alsa @ 0x1a948a0] ALSA buffer xrun.3903kB time=00:00:17.51 bitrate=6502.2kbits/s
[alsa @ 0x1a948a0] ALSA buffer xrun.6625kB time=00:00:21.89 bitrate=6221.4kbits/s
[alsa @ 0x1a948a0] ALSA buffer xrun.9548kB time=00:00:26.28 bitrate=6092.5kbits/s
^Cframe= 851 fps= 26 q=-1.0 Lsize= 22018kB time=00:00:30.69 bitrate=5875.3kbits/s
video:21996kB audio:12kB subtitle:0kB other streams:0kB global headers:4kB muxing overhead: 0.044897%
[libx264 @ 0x1aa8ac0] frame I:4 Avg QP:23.50 size: 62405
[libx264 @ 0x1aa8ac0] frame P:847 Avg QP:25.58 size: 26297
[libx264 @ 0x1aa8ac0] mb I I16..4: 100.0% 0.0% 0.0%
[libx264 @ 0x1aa8ac0] mb P I16..4: 13.2% 0.0% 0.0% P16..4: 72.0% 0.0% 0.0% 0.0% 0.0% skip:14.8%
[libx264 @ 0x1aa8ac0] coded y,uvDC,uvAC intra: 40.6% 81.0% 58.6% inter: 58.8% 72.7% 8.6%
[libx264 @ 0x1aa8ac0] i16 v,h,dc,p: 41% 28% 22% 9%
[libx264 @ 0x1aa8ac0] i8c dc,h,v,p: 54% 19% 16% 11%
[libx264 @ 0x1aa8ac0] kb/s:6345.60
Received signal 2: terminating.
ffmpeg’s detection of the ALSA stream is seemingly goofed up by the inconsistencies of the tape. In the failure case, only short blips of the tapes audio exist in the output MP4. The audio bitrate of the output file is less than 10 kbps, averaged out across the whole file. The output video seems to be fine, even though the low frames-per-second in the failure case log below.
The audio and video streams can be captured fine for short amounts of time before a source error occurs ; this provides the success case log. The failure case log was created by intentionally making an error in the source streams — turning on the camera makes a brief noisy signal.
Is there a setting that needs to be forced to keep ffmpeg recording the audio stream, even when the tape is blank or noisy ?
Could it be that the libfdk_aac audio encoder is tripped up by the low quality source ?
The relevant line ;
rawvideostream is piped to this in script at bottom :ffmpeg -pixel_format uyvy422 -s:v 720x480 -framerate 29.97 -f rawvideo \
-i $PIPE -f alsa -i hw:0,0 -vf scale=w=720:h=540 -vcodec libx264 \
-preset ultrafast -shortest -c:a libfdk_aac -b:a 128k -af pan=1:c0=c0 \
-ar 96000 $OUTFILEThe
arargument was one attempt to force recording.ffmpeg log file for (short-lived) success ; high frames-per-second captured :
ffmpeg version 2.5.3 Copyright (c) 2000-2015 the FFmpeg developers
built on Jan 11 2015 17:53:45 with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1)
configuration: --extra-libs=-ldl --prefix=/opt/ffmpeg --enable-avresample --disable-debug --enable-nonfree --enable-gpl --enable-version3 --enable-libpulse --enable-libopencore-amrnb --enable-libopencore-amrwb --disable-decoder=amrnb --disable-decoder=amrwb --enable-libx264 --enable-libx265 --enable-libfdk-aac --enable-libvorbis --enable-libmp3lame --enable-libopus --enable-libvpx --enable-libspeex --enable-libass --enable-avisynth --enable-libsoxr --enable-libxvid --enable-libvo-aacenc --enable-libvidstab
libavutil 54. 15.100 / 54. 15.100
libavcodec 56. 13.100 / 56. 13.100
libavformat 56. 15.102 / 56. 15.102
libavdevice 56. 3.100 / 56. 3.100
libavfilter 5. 2.103 / 5. 2.103
libavresample 2. 1. 0 / 2. 1. 0
libswscale 3. 1.101 / 3. 1.101
libswresample 1. 1.100 / 1. 1.100
libpostproc 53. 3.100 / 53. 3.100
Input #0, rawvideo, from '/tmp/somagic-pipe':
Duration: N/A, start: 0.000000, bitrate: 165722 kb/s
Stream #0:0: Video: rawvideo (UYVY / 0x59565955), uyvy422, 720x480, 165722 kb/s, 29.97 tbr, 29.97 tbn, 29.97 tbc
Home directory not accessible: Permission denied
Guessed Channel Layout for Input Stream #1.0 : stereo
Input #1, alsa, from 'hw:0,0':
Duration: N/A, start: 1423202268.577088, bitrate: 1536 kb/s
Stream #1:0: Audio: pcm_s16le, 48000 Hz, 2 channels, s16, 1536 kb/s
No pixel format specified, yuv422p for H.264 encoding chosen.
Use -pix_fmt yuv420p for compatibility with outdated media players.
[Parsed_pan_0 @ 0x3335d60] This syntax is deprecated. Use '|' to separate the list items.
Single channel layout '1' is interpreted as a number of channels, switch to the syntax '1c' otherwise it will be interpreted as a channel layout number in a later version
[Parsed_pan_0 @ 0x3335d60] Pure channel mapping detected: 0
[libx264 @ 0x3364bc0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.1 Cache64
[libx264 @ 0x3364bc0] profile High 4:2:2, level 3.1, 4:2:2 8-bit
[libx264 @ 0x3364bc0] 264 - core 142 r2389 956c8d8 - H.264/MPEG-4 AVC codec - Copyleft 2003-2014 - http://www.videolan.org/x264.html - options: cabac=0 ref=1 deblock=0:0:0 analyse=0:0 me=dia subme=0 psy=1 psy_rd=1.00:0.00 mixed_ref=0 me_range=16 chroma_me=1 trellis=0 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=0 threads=3 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=0 weightp=0 keyint=250 keyint_min=25 scenecut=0 intra_refresh=0 rc=crf mbtree=0 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=0
Output #0, mp4, to '/home/peterbecich/easycap/Videos/fpv_video_02_05_2015_21_57_48.mp4':
Metadata:
encoder : Lavf56.15.102
Stream #0:0: Video: h264 (libx264) ([33][0][0][0] / 0x0021), yuv422p, 720x540, q=-1--1, 29.97 fps, 11988 tbn, 29.97 tbc
Metadata:
encoder : Lavc56.13.100 libx264
Stream #0:1: Audio: aac (libfdk_aac) ([64][0][0][0] / 0x0040), 96000 Hz, mono, s16, 128 kb/s
Metadata:
encoder : Lavc56.13.100 libfdk_aac
Stream mapping:
Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (libx264))
Stream #1:0 -> #0:1 (pcm_s16le (native) -> aac (libfdk_aac))
Press [q] to stop, [?] for help
frame= 13 fps=0.0 q=26.0 size= 187kB time=00:00:00.30 bitrate=5102.7kbits/s
frame= 29 fps= 29 q=26.0 size= 469kB time=00:00:00.83 bitrate=4607.6kbits/s
frame= 44 fps= 29 q=26.0 size= 755kB time=00:00:01.33 bitrate=4635.2kbits/s
frame= 59 fps= 29 q=26.0 size= 1024kB time=00:00:01.83 bitrate=4572.1kbits/s
frame= 74 fps= 29 q=26.0 size= 1279kB time=00:00:02.33 bitrate=4486.5kbits/s
frame= 89 fps= 29 q=26.0 size= 1516kB time=00:00:02.83 bitrate=4378.0kbits/s
frame= 104 fps= 29 q=26.0 size= 1752kB time=00:00:03.33 bitrate=4301.0kbits/s
frame= 119 fps= 29 q=26.0 size= 1991kB time=00:00:03.83 bitrate=4251.1kbits/s
frame= 135 fps= 30 q=26.0 size= 2245kB time=00:00:04.37 bitrate=4207.5kbits/s
frame= 150 fps= 30 q=26.0 size= 2524kB time=00:00:04.87 bitrate=4245.0kbits/s
frame= 165 fps= 30 q=26.0 size= 2808kB time=00:00:05.37 bitrate=4282.0kbits/s
frame= 180 fps= 30 q=26.0 size= 3091kB time=00:00:05.87 bitrate=4311.5kbits/s
[rawvideo @ 0x3350640] Invalid buffer size, packet size 65536 < expected frame_size 691200
Error while decoding stream #0:0: Invalid argument
frame= 183 fps= 29 q=-1.0 Lsize= 3247kB time=00:00:06.11 bitrate=4351.5kbits/s
video:3142kB audio:96kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.254788%
[libx264 @ 0x3364bc0] frame I:1 Avg QP:20.00 size: 2289
[libx264 @ 0x3364bc0] frame P:182 Avg QP:25.99 size: 17664
[libx264 @ 0x3364bc0] mb I I16..4: 100.0% 0.0% 0.0%
[libx264 @ 0x3364bc0] mb P I16..4: 78.5% 0.0% 0.0% P16..4: 20.2% 0.0% 0.0% 0.0% 0.0% skip: 1.4%
[libx264 @ 0x3364bc0] coded y,uvDC,uvAC intra: 84.1% 71.5% 18.9% inter: 51.9% 63.5% 0.4%
[libx264 @ 0x3364bc0] i16 v,h,dc,p: 15% 8% 69% 8%
[libx264 @ 0x3364bc0] i8c dc,h,v,p: 50% 19% 24% 7%
[libx264 @ 0x3364bc0] kb/s:4215.02ffmpeg log for failure ; low FPS captured :
ffmpeg version 2.5.3 Copyright (c) 2000-2015 the FFmpeg developers
built on Jan 11 2015 17:53:45 with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1)
configuration: --extra-libs=-ldl --prefix=/opt/ffmpeg --enable-avresample --disable-debug --enable-nonfree --enable-gpl --enable-version3 --enable-libpulse --enable-libopencore-amrnb --enable-libopencore-amrwb --disable-decoder=amrnb --disable-decoder=amrwb --enable-libx264 --enable-libx265 --enable-libfdk-aac --enable-libvorbis --enable-libmp3lame --enable-libopus --enable-libvpx --enable-libspeex --enable-libass --enable-avisynth --enable-libsoxr --enable-libxvid --enable-libvo-aacenc --enable-libvidstab
libavutil 54. 15.100 / 54. 15.100
libavcodec 56. 13.100 / 56. 13.100
libavformat 56. 15.102 / 56. 15.102
libavdevice 56. 3.100 / 56. 3.100
libavfilter 5. 2.103 / 5. 2.103
libavresample 2. 1. 0 / 2. 1. 0
libswscale 3. 1.101 / 3. 1.101
libswresample 1. 1.100 / 1. 1.100
libpostproc 53. 3.100 / 53. 3.100
Input #0, rawvideo, from '/tmp/somagic-pipe':
Duration: N/A, start: 0.000000, bitrate: 165722 kb/s
Stream #0:0: Video: rawvideo (UYVY / 0x59565955), uyvy422, 720x480, 165722 kb/s, 29.97 tbr, 29.97 tbn, 29.97 tbc
Home directory not accessible: Permission denied
Guessed Channel Layout for Input Stream #1.0 : stereo
Input #1, alsa, from 'hw:0,0':
Duration: N/A, start: 1423201999.226455, bitrate: 1536 kb/s
Stream #1:0: Audio: pcm_s16le, 48000 Hz, 2 channels, s16, 1536 kb/s
No pixel format specified, yuv422p for H.264 encoding chosen.
Use -pix_fmt yuv420p for compatibility with outdated media players.
[Parsed_pan_0 @ 0x21cad60] This syntax is deprecated. Use '|' to separate the list items.
Single channel layout '1' is interpreted as a number of channels, switch to the syntax '1c' otherwise it will be interpreted as a channel layout number in a later version
[Parsed_pan_0 @ 0x21cad60] Pure channel mapping detected: 0
[libx264 @ 0x21f9bc0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.1 Cache64
[libx264 @ 0x21f9bc0] profile High 4:2:2, level 3.1, 4:2:2 8-bit
[libx264 @ 0x21f9bc0] 264 - core 142 r2389 956c8d8 - H.264/MPEG-4 AVC codec - Copyleft 2003-2014 - http://www.videolan.org/x264.html - options: cabac=0 ref=1 deblock=0:0:0 analyse=0:0 me=dia subme=0 psy=1 psy_rd=1.00:0.00 mixed_ref=0 me_range=16 chroma_me=1 trellis=0 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=0 threads=3 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=0 weightp=0 keyint=250 keyint_min=25 scenecut=0 intra_refresh=0 rc=crf mbtree=0 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=0
Output #0, mp4, to '/home/peterbecich/easycap/Videos/fpv_video_02_05_2015_21_53_18.mp4':
Metadata:
encoder : Lavf56.15.102
Stream #0:0: Video: h264 (libx264) ([33][0][0][0] / 0x0021), yuv422p, 720x540, q=-1--1, 29.97 fps, 11988 tbn, 29.97 tbc
Metadata:
encoder : Lavc56.13.100 libx264
Stream #0:1: Audio: aac (libfdk_aac) ([64][0][0][0] / 0x0040), 96000 Hz, mono, s16, 128 kb/s
Metadata:
encoder : Lavc56.13.100 libfdk_aac
Stream mapping:
Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (libx264))
Stream #1:0 -> #0:1 (pcm_s16le (native) -> aac (libfdk_aac))
Press [q] to stop, [?] for help
frame= 1 fps=0.0 q=0.0 size= 0kB time=00:00:00.00 bitrate=N/A
frame= 1 fps=1.0 q=0.0 size= 0kB time=00:00:00.00 bitrate=N/A
frame= 1 fps=0.7 q=0.0 size= 0kB time=00:00:00.00 bitrate=N/A
frame= 1 fps=0.5 q=0.0 size= 0kB time=00:00:00.00 bitrate=N/A
frame= 1 fps=0.4 q=0.0 size= 0kB time=00:00:00.00 bitrate=N/A
frame= 1 fps=0.3 q=0.0 size= 0kB time=00:00:00.00 bitrate=N/A
frame= 1 fps=0.3 q=0.0 size= 0kB time=00:00:00.00 bitrate=N/A
frame= 1 fps=0.2 q=0.0 size= 0kB time=00:00:00.00 bitrate=N/A
frame= 1 fps=0.2 q=0.0 size= 0kB time=00:00:00.00 bitrate=N/A
frame= 1 fps=0.2 q=0.0 size= 0kB time=00:00:00.00 bitrate=N/A
frame= 1 fps=0.2 q=0.0 size= 0kB time=00:00:00.00 bitrate=N/A
[alsa @ 0x21e5ac0] ALSA buffer xrun.
frame= 8 fps=1.3 q=19.0 size= 12kB time=00:00:06.03 bitrate= 15.9kbits/s
frame= 23 fps=3.5 q=18.0 size= 12kB time=00:00:06.03 bitrate= 16.4kbits/s
frame= 38 fps=5.4 q=18.0 size= 12kB time=00:00:06.03 bitrate= 16.7kbits/s
frame= 53 fps=7.0 q=18.0 size= 12kB time=00:00:06.03 bitrate= 16.9kbits/s
frame= 68 fps=8.4 q=26.0 size= 146kB time=00:00:06.03 bitrate= 198.8kbits/s
frame= 83 fps=9.7 q=26.0 size= 375kB time=00:00:06.03 bitrate= 510.0kbits/s
frame= 98 fps= 11 q=26.0 size= 608kB time=00:00:06.03 bitrate= 826.5kbits/s
frame= 114 fps= 12 q=26.0 size= 875kB time=00:00:06.03 bitrate=1189.1kbits/s
frame= 128 fps= 13 q=26.0 size= 1091kB time=00:00:06.03 bitrate=1481.6kbits/s
frame= 144 fps= 14 q=26.0 size= 1339kB time=00:00:06.03 bitrate=1819.2kbits/s
frame= 159 fps= 14 q=26.0 size= 1571kB time=00:00:06.03 bitrate=2134.6kbits/s
frame= 174 fps= 15 q=26.0 size= 1796kB time=00:00:06.03 bitrate=2440.1kbits/s
[alsa @ 0x21e5ac0] ALSA buffer xrun.
frame= 189 fps= 16 q=26.0 size= 2015kB time=00:00:12.04 bitrate=1370.4kbits/s
frame= 204 fps= 16 q=26.0 size= 2238kB time=00:00:12.04 bitrate=1522.3kbits/s
frame= 219 fps= 17 q=26.0 size= 2490kB time=00:00:12.04 bitrate=1694.2kbits/s
frame= 235 fps= 17 q=26.0 size= 2728kB time=00:00:12.04 bitrate=1855.8kbits/s
frame= 250 fps= 18 q=26.0 size= 2973kB time=00:00:12.04 bitrate=2022.4kbits/s
[rawvideo @ 0x21e5640] Invalid buffer size, packet size 65536 < expected frame_size 691200
Error while decoding stream #0:0: Invalid argument
frame= 261 fps= 18 q=-1.0 Lsize= 3269kB time=00:00:12.06 bitrate=2220.1kbits/s
video:3263kB audio:4kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.081101%
[libx264 @ 0x21f9bc0] frame I:2 Avg QP:21.50 size: 21342
[libx264 @ 0x21f9bc0] frame P:259 Avg QP:24.22 size: 12734
[libx264 @ 0x21f9bc0] mb I I16..4: 100.0% 0.0% 0.0%
[libx264 @ 0x21f9bc0] mb P I16..4: 62.8% 0.0% 0.0% P16..4: 14.2% 0.0% 0.0% 0.0% 0.0% skip:22.9%
[libx264 @ 0x21f9bc0] coded y,uvDC,uvAC intra: 77.7% 61.2% 14.1% inter: 19.7% 24.8% 1.6%
[libx264 @ 0x21f9bc0] i16 v,h,dc,p: 17% 10% 65% 8%
[libx264 @ 0x21f9bc0] i8c dc,h,v,p: 52% 18% 24% 6%
[libx264 @ 0x21f9bc0] kb/s:3068.90The whole script :
#!/bin/sh
PIPE=/tmp/somagic-pipe
OUTFILEDIR=~/easycap/Videos/
LOGDIR=~/.somagic-log/
NOW=`date +"%m_%d_%Y_%H_%M_%S"`
OUTFILE=${OUTFILEDIR}fpv_video_${NOW}.mp4
mkdir $LOGDIR
FFMPEG_LOG=${LOGDIR}ffmpeg.log
SOMAGIC_LOG=${LOGDIR}somagic.log
MPLAYER_LOG=${LOGDIR}mplayer.log
rm $PIPE >/dev/null 2>&1
rm $OUTFILE >/dev/null 2>&1
rm $FFMPEG_LOG
rm $SOMAGIC_LOG
rm $MPLAYER_LOG
mkfifo $PIPE >/dev/null 2>&1
ffmpeg -pixel_format uyvy422 -s:v 720x480 -framerate 29.97 -f rawvideo \
-i $PIPE -f alsa -i hw:0,0 -vf scale=w=720:h=540 -vcodec libx264 \
-preset ultrafast -shortest -c:a libfdk_aac -b:a 128k -af pan=1:c0=c0 \
-ar 96000 $OUTFILE > $FFMPEG_LOG 2>&1 &
somagic-capture --ntsc -c --luminance=2 --lum-aperture=3 2> $SOMAGIC_LOG \
| tee $PIPE | \
mplayer -vf yadif,screenshot -demuxer rawvideo -rawvideo \
"ntsc:format=uyvy:fps=30000/1001" -aspect 4:3 - 2> $MPLAYER_LOG
rm $PIPE >/dev/null 2>&1Modified from here : https://gist.github.com/Brick85/0b327ac2d3d45e23ed33
-
Forcing ffmpeg to capture unreliable ALSA audio stream
6 février 2015, par Peter BecichI am attempting to transfer some old Video 8 tapes to my computer, though an EasyCap USB stick and the motherboard’s sound line-in, on Ubuntu. I believe the arguments are correctly laid out below to capture from two independent streams, and encode them both into the output MP4 file.
ffmpeg’s detection of the ALSA stream is seemingly goofed up by the inconsistencies of the tape. In the failure case, only short blips of the tapes audio exist in the output MP4. The audio bitrate of the output file is less than 10 kbps, averaged out across the whole file. The output video seems to be fine, even though the low frames-per-second in the failure case log below.
The audio and video streams can be captured fine for short amounts of time before a source error occurs ; this provides the success case log. The failure case log was created by intentionally making an error in the source streams — turning on the camera makes a brief noisy signal.
Is there a setting that needs to be forced to keep ffmpeg recording the audio stream, even when the tape is blank or noisy ?
Could it be that the libfdk_aac audio encoder is tripped up by the low quality source ?
The relevant line ;
rawvideostream is piped to this in script at bottom :ffmpeg -pixel_format uyvy422 -s:v 720x480 -framerate 29.97 -f rawvideo \
-i $PIPE -f alsa -i hw:0,0 -vf scale=w=720:h=540 -vcodec libx264 \
-preset ultrafast -shortest -c:a libfdk_aac -b:a 128k -af pan=1:c0=c0 \
-ar 96000 $OUTFILEThe
arargument was one attempt to force recording.ffmpeg log file for (short-lived) success ; high frames-per-second captured :
ffmpeg version 2.5.3 Copyright (c) 2000-2015 the FFmpeg developers
built on Jan 11 2015 17:53:45 with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1)
configuration: --extra-libs=-ldl --prefix=/opt/ffmpeg --enable-avresample --disable-debug --enable-nonfree --enable-gpl --enable-version3 --enable-libpulse --enable-libopencore-amrnb --enable-libopencore-amrwb --disable-decoder=amrnb --disable-decoder=amrwb --enable-libx264 --enable-libx265 --enable-libfdk-aac --enable-libvorbis --enable-libmp3lame --enable-libopus --enable-libvpx --enable-libspeex --enable-libass --enable-avisynth --enable-libsoxr --enable-libxvid --enable-libvo-aacenc --enable-libvidstab
libavutil 54. 15.100 / 54. 15.100
libavcodec 56. 13.100 / 56. 13.100
libavformat 56. 15.102 / 56. 15.102
libavdevice 56. 3.100 / 56. 3.100
libavfilter 5. 2.103 / 5. 2.103
libavresample 2. 1. 0 / 2. 1. 0
libswscale 3. 1.101 / 3. 1.101
libswresample 1. 1.100 / 1. 1.100
libpostproc 53. 3.100 / 53. 3.100
Input #0, rawvideo, from '/tmp/somagic-pipe':
Duration: N/A, start: 0.000000, bitrate: 165722 kb/s
Stream #0:0: Video: rawvideo (UYVY / 0x59565955), uyvy422, 720x480, 165722 kb/s, 29.97 tbr, 29.97 tbn, 29.97 tbc
Home directory not accessible: Permission denied
Guessed Channel Layout for Input Stream #1.0 : stereo
Input #1, alsa, from 'hw:0,0':
Duration: N/A, start: 1423202268.577088, bitrate: 1536 kb/s
Stream #1:0: Audio: pcm_s16le, 48000 Hz, 2 channels, s16, 1536 kb/s
No pixel format specified, yuv422p for H.264 encoding chosen.
Use -pix_fmt yuv420p for compatibility with outdated media players.
[Parsed_pan_0 @ 0x3335d60] This syntax is deprecated. Use '|' to separate the list items.
Single channel layout '1' is interpreted as a number of channels, switch to the syntax '1c' otherwise it will be interpreted as a channel layout number in a later version
[Parsed_pan_0 @ 0x3335d60] Pure channel mapping detected: 0
[libx264 @ 0x3364bc0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.1 Cache64
[libx264 @ 0x3364bc0] profile High 4:2:2, level 3.1, 4:2:2 8-bit
[libx264 @ 0x3364bc0] 264 - core 142 r2389 956c8d8 - H.264/MPEG-4 AVC codec - Copyleft 2003-2014 - http://www.videolan.org/x264.html - options: cabac=0 ref=1 deblock=0:0:0 analyse=0:0 me=dia subme=0 psy=1 psy_rd=1.00:0.00 mixed_ref=0 me_range=16 chroma_me=1 trellis=0 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=0 threads=3 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=0 weightp=0 keyint=250 keyint_min=25 scenecut=0 intra_refresh=0 rc=crf mbtree=0 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=0
Output #0, mp4, to '/home/peterbecich/easycap/Videos/fpv_video_02_05_2015_21_57_48.mp4':
Metadata:
encoder : Lavf56.15.102
Stream #0:0: Video: h264 (libx264) ([33][0][0][0] / 0x0021), yuv422p, 720x540, q=-1--1, 29.97 fps, 11988 tbn, 29.97 tbc
Metadata:
encoder : Lavc56.13.100 libx264
Stream #0:1: Audio: aac (libfdk_aac) ([64][0][0][0] / 0x0040), 96000 Hz, mono, s16, 128 kb/s
Metadata:
encoder : Lavc56.13.100 libfdk_aac
Stream mapping:
Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (libx264))
Stream #1:0 -> #0:1 (pcm_s16le (native) -> aac (libfdk_aac))
Press [q] to stop, [?] for help
frame= 13 fps=0.0 q=26.0 size= 187kB time=00:00:00.30 bitrate=5102.7kbits/s
frame= 29 fps= 29 q=26.0 size= 469kB time=00:00:00.83 bitrate=4607.6kbits/s
frame= 44 fps= 29 q=26.0 size= 755kB time=00:00:01.33 bitrate=4635.2kbits/s
frame= 59 fps= 29 q=26.0 size= 1024kB time=00:00:01.83 bitrate=4572.1kbits/s
frame= 74 fps= 29 q=26.0 size= 1279kB time=00:00:02.33 bitrate=4486.5kbits/s
frame= 89 fps= 29 q=26.0 size= 1516kB time=00:00:02.83 bitrate=4378.0kbits/s
frame= 104 fps= 29 q=26.0 size= 1752kB time=00:00:03.33 bitrate=4301.0kbits/s
frame= 119 fps= 29 q=26.0 size= 1991kB time=00:00:03.83 bitrate=4251.1kbits/s
frame= 135 fps= 30 q=26.0 size= 2245kB time=00:00:04.37 bitrate=4207.5kbits/s
frame= 150 fps= 30 q=26.0 size= 2524kB time=00:00:04.87 bitrate=4245.0kbits/s
frame= 165 fps= 30 q=26.0 size= 2808kB time=00:00:05.37 bitrate=4282.0kbits/s
frame= 180 fps= 30 q=26.0 size= 3091kB time=00:00:05.87 bitrate=4311.5kbits/s
[rawvideo @ 0x3350640] Invalid buffer size, packet size 65536 < expected frame_size 691200
Error while decoding stream #0:0: Invalid argument
frame= 183 fps= 29 q=-1.0 Lsize= 3247kB time=00:00:06.11 bitrate=4351.5kbits/s
video:3142kB audio:96kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.254788%
[libx264 @ 0x3364bc0] frame I:1 Avg QP:20.00 size: 2289
[libx264 @ 0x3364bc0] frame P:182 Avg QP:25.99 size: 17664
[libx264 @ 0x3364bc0] mb I I16..4: 100.0% 0.0% 0.0%
[libx264 @ 0x3364bc0] mb P I16..4: 78.5% 0.0% 0.0% P16..4: 20.2% 0.0% 0.0% 0.0% 0.0% skip: 1.4%
[libx264 @ 0x3364bc0] coded y,uvDC,uvAC intra: 84.1% 71.5% 18.9% inter: 51.9% 63.5% 0.4%
[libx264 @ 0x3364bc0] i16 v,h,dc,p: 15% 8% 69% 8%
[libx264 @ 0x3364bc0] i8c dc,h,v,p: 50% 19% 24% 7%
[libx264 @ 0x3364bc0] kb/s:4215.02ffmpeg log for failure ; low FPS captured :
ffmpeg version 2.5.3 Copyright (c) 2000-2015 the FFmpeg developers
built on Jan 11 2015 17:53:45 with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1)
configuration: --extra-libs=-ldl --prefix=/opt/ffmpeg --enable-avresample --disable-debug --enable-nonfree --enable-gpl --enable-version3 --enable-libpulse --enable-libopencore-amrnb --enable-libopencore-amrwb --disable-decoder=amrnb --disable-decoder=amrwb --enable-libx264 --enable-libx265 --enable-libfdk-aac --enable-libvorbis --enable-libmp3lame --enable-libopus --enable-libvpx --enable-libspeex --enable-libass --enable-avisynth --enable-libsoxr --enable-libxvid --enable-libvo-aacenc --enable-libvidstab
libavutil 54. 15.100 / 54. 15.100
libavcodec 56. 13.100 / 56. 13.100
libavformat 56. 15.102 / 56. 15.102
libavdevice 56. 3.100 / 56. 3.100
libavfilter 5. 2.103 / 5. 2.103
libavresample 2. 1. 0 / 2. 1. 0
libswscale 3. 1.101 / 3. 1.101
libswresample 1. 1.100 / 1. 1.100
libpostproc 53. 3.100 / 53. 3.100
Input #0, rawvideo, from '/tmp/somagic-pipe':
Duration: N/A, start: 0.000000, bitrate: 165722 kb/s
Stream #0:0: Video: rawvideo (UYVY / 0x59565955), uyvy422, 720x480, 165722 kb/s, 29.97 tbr, 29.97 tbn, 29.97 tbc
Home directory not accessible: Permission denied
Guessed Channel Layout for Input Stream #1.0 : stereo
Input #1, alsa, from 'hw:0,0':
Duration: N/A, start: 1423201999.226455, bitrate: 1536 kb/s
Stream #1:0: Audio: pcm_s16le, 48000 Hz, 2 channels, s16, 1536 kb/s
No pixel format specified, yuv422p for H.264 encoding chosen.
Use -pix_fmt yuv420p for compatibility with outdated media players.
[Parsed_pan_0 @ 0x21cad60] This syntax is deprecated. Use '|' to separate the list items.
Single channel layout '1' is interpreted as a number of channels, switch to the syntax '1c' otherwise it will be interpreted as a channel layout number in a later version
[Parsed_pan_0 @ 0x21cad60] Pure channel mapping detected: 0
[libx264 @ 0x21f9bc0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.1 Cache64
[libx264 @ 0x21f9bc0] profile High 4:2:2, level 3.1, 4:2:2 8-bit
[libx264 @ 0x21f9bc0] 264 - core 142 r2389 956c8d8 - H.264/MPEG-4 AVC codec - Copyleft 2003-2014 - http://www.videolan.org/x264.html - options: cabac=0 ref=1 deblock=0:0:0 analyse=0:0 me=dia subme=0 psy=1 psy_rd=1.00:0.00 mixed_ref=0 me_range=16 chroma_me=1 trellis=0 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=0 threads=3 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=0 weightp=0 keyint=250 keyint_min=25 scenecut=0 intra_refresh=0 rc=crf mbtree=0 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=0
Output #0, mp4, to '/home/peterbecich/easycap/Videos/fpv_video_02_05_2015_21_53_18.mp4':
Metadata:
encoder : Lavf56.15.102
Stream #0:0: Video: h264 (libx264) ([33][0][0][0] / 0x0021), yuv422p, 720x540, q=-1--1, 29.97 fps, 11988 tbn, 29.97 tbc
Metadata:
encoder : Lavc56.13.100 libx264
Stream #0:1: Audio: aac (libfdk_aac) ([64][0][0][0] / 0x0040), 96000 Hz, mono, s16, 128 kb/s
Metadata:
encoder : Lavc56.13.100 libfdk_aac
Stream mapping:
Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (libx264))
Stream #1:0 -> #0:1 (pcm_s16le (native) -> aac (libfdk_aac))
Press [q] to stop, [?] for help
frame= 1 fps=0.0 q=0.0 size= 0kB time=00:00:00.00 bitrate=N/A
frame= 1 fps=1.0 q=0.0 size= 0kB time=00:00:00.00 bitrate=N/A
frame= 1 fps=0.7 q=0.0 size= 0kB time=00:00:00.00 bitrate=N/A
frame= 1 fps=0.5 q=0.0 size= 0kB time=00:00:00.00 bitrate=N/A
frame= 1 fps=0.4 q=0.0 size= 0kB time=00:00:00.00 bitrate=N/A
frame= 1 fps=0.3 q=0.0 size= 0kB time=00:00:00.00 bitrate=N/A
frame= 1 fps=0.3 q=0.0 size= 0kB time=00:00:00.00 bitrate=N/A
frame= 1 fps=0.2 q=0.0 size= 0kB time=00:00:00.00 bitrate=N/A
frame= 1 fps=0.2 q=0.0 size= 0kB time=00:00:00.00 bitrate=N/A
frame= 1 fps=0.2 q=0.0 size= 0kB time=00:00:00.00 bitrate=N/A
frame= 1 fps=0.2 q=0.0 size= 0kB time=00:00:00.00 bitrate=N/A
[alsa @ 0x21e5ac0] ALSA buffer xrun.
frame= 8 fps=1.3 q=19.0 size= 12kB time=00:00:06.03 bitrate= 15.9kbits/s
frame= 23 fps=3.5 q=18.0 size= 12kB time=00:00:06.03 bitrate= 16.4kbits/s
frame= 38 fps=5.4 q=18.0 size= 12kB time=00:00:06.03 bitrate= 16.7kbits/s
frame= 53 fps=7.0 q=18.0 size= 12kB time=00:00:06.03 bitrate= 16.9kbits/s
frame= 68 fps=8.4 q=26.0 size= 146kB time=00:00:06.03 bitrate= 198.8kbits/s
frame= 83 fps=9.7 q=26.0 size= 375kB time=00:00:06.03 bitrate= 510.0kbits/s
frame= 98 fps= 11 q=26.0 size= 608kB time=00:00:06.03 bitrate= 826.5kbits/s
frame= 114 fps= 12 q=26.0 size= 875kB time=00:00:06.03 bitrate=1189.1kbits/s
frame= 128 fps= 13 q=26.0 size= 1091kB time=00:00:06.03 bitrate=1481.6kbits/s
frame= 144 fps= 14 q=26.0 size= 1339kB time=00:00:06.03 bitrate=1819.2kbits/s
frame= 159 fps= 14 q=26.0 size= 1571kB time=00:00:06.03 bitrate=2134.6kbits/s
frame= 174 fps= 15 q=26.0 size= 1796kB time=00:00:06.03 bitrate=2440.1kbits/s
[alsa @ 0x21e5ac0] ALSA buffer xrun.
frame= 189 fps= 16 q=26.0 size= 2015kB time=00:00:12.04 bitrate=1370.4kbits/s
frame= 204 fps= 16 q=26.0 size= 2238kB time=00:00:12.04 bitrate=1522.3kbits/s
frame= 219 fps= 17 q=26.0 size= 2490kB time=00:00:12.04 bitrate=1694.2kbits/s
frame= 235 fps= 17 q=26.0 size= 2728kB time=00:00:12.04 bitrate=1855.8kbits/s
frame= 250 fps= 18 q=26.0 size= 2973kB time=00:00:12.04 bitrate=2022.4kbits/s
[rawvideo @ 0x21e5640] Invalid buffer size, packet size 65536 < expected frame_size 691200
Error while decoding stream #0:0: Invalid argument
frame= 261 fps= 18 q=-1.0 Lsize= 3269kB time=00:00:12.06 bitrate=2220.1kbits/s
video:3263kB audio:4kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.081101%
[libx264 @ 0x21f9bc0] frame I:2 Avg QP:21.50 size: 21342
[libx264 @ 0x21f9bc0] frame P:259 Avg QP:24.22 size: 12734
[libx264 @ 0x21f9bc0] mb I I16..4: 100.0% 0.0% 0.0%
[libx264 @ 0x21f9bc0] mb P I16..4: 62.8% 0.0% 0.0% P16..4: 14.2% 0.0% 0.0% 0.0% 0.0% skip:22.9%
[libx264 @ 0x21f9bc0] coded y,uvDC,uvAC intra: 77.7% 61.2% 14.1% inter: 19.7% 24.8% 1.6%
[libx264 @ 0x21f9bc0] i16 v,h,dc,p: 17% 10% 65% 8%
[libx264 @ 0x21f9bc0] i8c dc,h,v,p: 52% 18% 24% 6%
[libx264 @ 0x21f9bc0] kb/s:3068.90The whole script :
#!/bin/sh
PIPE=/tmp/somagic-pipe
OUTFILEDIR=~/easycap/Videos/
LOGDIR=~/.somagic-log/
NOW=`date +"%m_%d_%Y_%H_%M_%S"`
OUTFILE=${OUTFILEDIR}fpv_video_${NOW}.mp4
mkdir $LOGDIR
FFMPEG_LOG=${LOGDIR}ffmpeg.log
SOMAGIC_LOG=${LOGDIR}somagic.log
MPLAYER_LOG=${LOGDIR}mplayer.log
rm $PIPE >/dev/null 2>&1
rm $OUTFILE >/dev/null 2>&1
rm $FFMPEG_LOG
rm $SOMAGIC_LOG
rm $MPLAYER_LOG
mkfifo $PIPE >/dev/null 2>&1
ffmpeg -pixel_format uyvy422 -s:v 720x480 -framerate 29.97 -f rawvideo \
-i $PIPE -f alsa -i hw:0,0 -vf scale=w=720:h=540 -vcodec libx264 \
-preset ultrafast -shortest -c:a libfdk_aac -b:a 128k -af pan=1:c0=c0 \
-ar 96000 $OUTFILE > $FFMPEG_LOG 2>&1 &
somagic-capture --ntsc -c --luminance=2 --lum-aperture=3 2> $SOMAGIC_LOG \
| tee $PIPE | \
mplayer -vf yadif,screenshot -demuxer rawvideo -rawvideo \
"ntsc:format=uyvy:fps=30000/1001" -aspect 4:3 - 2> $MPLAYER_LOG
rm $PIPE >/dev/null 2>&1Modified from here : https://gist.github.com/Brick85/0b327ac2d3d45e23ed33
-
I want to take any Audio from a file and encode it as PCM_ALAW. My Example is a .m4a file to .wav file
22 novembre 2023, par ClockmanI have been working on this for a while now while am generally new to ffmpeg library, I have studied it a bit. The challenge I have that at the point of witting to file I get the following exception.


"Exception thrown at 0x00007FFACA8305B3 (avformat-60.dll) in FfmpegPractice.exe : 0xC0000005 : Access violation writing location 0x0000000000000000.". I understand this means am writing to an uninitialized buffer am unable to discover why this is happening. The exception call stack shows the following


avformat-60.dll!avformat_write_header() C
avformat-60.dll!ff_write_chained() C
avformat-60.dll!ff_write_chained() C
avformat-60.dll!av_write_frame() C
FfmpegPractice.exe!main() Line 215 C++


Some things I have tried


This code is part of a larger project built with CMake but for some reason I could no step into ffmpeg library while debugging, So I recompiled ffmpeg ensured debugging was enabled so I could drill down to the root cause but I still could not step into the ffmpeg library.


I then created a minimal project using visual studio c++ console project and I still could not step into the code.


I have read through many ffmpeg docs and some I could find on the internet and I still could not solve it.


This is the code


#include <iostream>

extern "C" {
#include <libavcodec></libavcodec>avcodec.h>
#include <libavformat></libavformat>avformat.h>
#include <libswresample></libswresample>swresample.h>
#include <libavutil></libavutil>opt.h>
#include <libavutil></libavutil>audio_fifo.h>
}

using namespace std;

//in audio file
string filename{ "rapid_caller_test.m4a" };
AVFormatContext* pFormatCtx{};
AVCodecContext* pCodecCtx{};
AVStream* pStream{};

//out audio file
string outFilename{ "output.wav" };
AVFormatContext* pOutFormatCtx{ nullptr };
AVCodecContext* pOutCodecCtx{ nullptr };
AVIOContext* pOutIoContext{ nullptr };
const AVCodec* pOutCodec{ nullptr };
AVStream* pOutStream{ nullptr };
const int OUTPUT_CHANNELS = 1;
const int SAMPLE_RATE = 8000;
const int OUT_BIT_RATE = 64000;
uint8_t** convertedSamplesBuffer{ nullptr };
int64_t dstNmbrSamples{ 0 };
int dstLineSize{ 0 };
static int64_t pts{ 0 };

//conversion context;
SwrContext* swr{};

uint32_t i{ 0 };
int audiostream{ -1 };


void cleanUp() 
{
 avcodec_free_context(&pOutCodecCtx);;
 avio_closep(&(pOutFormatCtx)->pb);
 avformat_free_context(pOutFormatCtx);
 pOutFormatCtx = nullptr;
}

int main()
{

/*
* section to setup input file
*/
if (avformat_open_input(&pFormatCtx, filename.data(), nullptr, nullptr) != 0) {
 cout << "could not open file " << filename << endl;
 return -1;
}
if (avformat_find_stream_info(pFormatCtx, nullptr) < 0) {
 cout << "Could not retrieve stream information from file " << filename << endl;
 return -1;
}
av_dump_format(pFormatCtx, 0, filename.c_str(), 0);

for (i = 0; i < pFormatCtx->nb_streams; i++) {
 if (pFormatCtx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
 audiostream = i;
 break;
 }
}
if (audiostream == -1) {
 cout << "did not find audio stream" << endl;
 return -1;
}

pStream = pFormatCtx->streams[audiostream];
const AVCodec* pCodec{ avcodec_find_decoder(pStream->codecpar->codec_id) };
pCodecCtx = avcodec_alloc_context3(pCodec);
avcodec_parameters_to_context(pCodecCtx, pStream->codecpar);
if (avcodec_open2(pCodecCtx, pCodec, nullptr)) {
 cout << "could not open codec" << endl;
 return -1;
}

/*
* section to set up output file which is a G711 audio
*/
if (avio_open(&pOutIoContext, outFilename.data(), AVIO_FLAG_WRITE)) {
 cout << "could not open out put file" << endl;
 return -1;
}
if (!(pOutFormatCtx = avformat_alloc_context())) {
 cout << "could not create format conext" << endl;
 cleanUp();
 return -1;
}
pOutFormatCtx->pb = pOutIoContext;
if (!(pOutFormatCtx->oformat = av_guess_format(nullptr, outFilename.data(), nullptr))) {
 cout << "could not find output file format" << endl;
 cleanUp();
 return -1;
}
if (!(pOutFormatCtx->url = av_strdup(outFilename.data()))) {
 cout << "could not allocate file name" << endl;
 cleanUp();
 return -1;
}
if (!(pOutCodec = avcodec_find_encoder(AV_CODEC_ID_PCM_ALAW))) {
 cout << "codec not found" << endl;
 cleanUp();
 return -1;
}
if (!(pOutStream = avformat_new_stream(pOutFormatCtx, nullptr))) {
 cout << "could not create new stream" << endl;
 cleanUp();
 return -1;
}
if (!(pOutCodecCtx = avcodec_alloc_context3(pOutCodec))) {
 cout << "could not allocate codec context" << endl;
 return -1;
}
av_channel_layout_default(&pOutCodecCtx->ch_layout, OUTPUT_CHANNELS);
pOutCodecCtx->sample_rate = SAMPLE_RATE;
pOutCodecCtx->sample_fmt = pOutCodec->sample_fmts[0];
pOutCodecCtx->bit_rate = OUT_BIT_RATE;

//setting sample rate for the container
pOutStream->time_base.den = SAMPLE_RATE;
pOutStream->time_base.num = 1;
if (pOutFormatCtx->oformat->flags & AVFMT_GLOBALHEADER)
 pOutCodecCtx->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;

if (avcodec_open2(pOutCodecCtx, pOutCodec, nullptr)) {
 cout << "could not open output codec" << endl;
 cleanUp();
 return -1;
}
if ((avcodec_parameters_from_context(pOutStream->codecpar, pOutCodecCtx)) < 0) {
 cout << "could not initialize stream parameters" << endl;
} 

AVPacket* packet = av_packet_alloc();

swr = swr_alloc();
swr_alloc_set_opts2(&swr, &pOutCodecCtx->ch_layout, pOutCodecCtx->sample_fmt, pOutCodecCtx->sample_rate,&pCodecCtx->ch_layout, pCodecCtx->sample_fmt, pCodecCtx->sample_rate, 0, nullptr);
swr_init(swr);

int ret{};
int bSize{};
while (av_read_frame(pFormatCtx, packet) >= 0) {
 AVFrame* pFrame = av_frame_alloc();
 AVFrame* pOutFrame = av_frame_alloc();
 if (packet->stream_index == audiostream) {
 ret = avcodec_send_packet(pCodecCtx, packet);
 while (ret >= 0) {
 ret = avcodec_receive_frame(pCodecCtx, pFrame);
 if (ret == AVERROR(EAGAIN))
 continue;
 else if (ret == AVERROR_EOF)
 break;
 dstNmbrSamples = av_rescale_rnd(swr_get_delay(swr, pCodecCtx->sample_rate) + pFrame->nb_samples, pOutCodecCtx->sample_rate, pCodecCtx->sample_rate, AV_ROUND_UP);
 if ((av_samples_alloc_array_and_samples(&convertedSamplesBuffer, &dstLineSize, pOutCodecCtx->ch_layout.nb_channels,dstNmbrSamples, pOutCodecCtx->sample_fmt, 0)) < 0) {
 cout << "coult not allocate samples array and buffer" << endl;
 }
 int channel_samples_count{ 0 };
 channel_samples_count = swr_convert(swr, convertedSamplesBuffer, dstNmbrSamples, (const uint8_t**)pFrame->data, pFrame->nb_samples);
 bSize = av_samples_get_buffer_size(&dstLineSize, pOutCodecCtx->ch_layout.nb_channels, channel_samples_count, pOutCodecCtx->sample_fmt, 0);
 cout << "no of samples is " << channel_samples_count << " the buffer size " << bSize << endl;
 pOutFrame->nb_samples = channel_samples_count;
 av_channel_layout_copy(&pOutFrame->ch_layout, &pOutCodecCtx->ch_layout);
 pOutFrame->format = pOutCodecCtx->sample_fmt;
 pOutFrame->sample_rate = pOutCodecCtx->sample_rate;
 if ((av_frame_get_buffer(pOutFrame, 0)) < 0) {
 cout << "could not allocate output frame samples " << endl;
 av_frame_free(&pOutFrame);
 }
 
 //populate out frame buffer
 av_frame_make_writable(pOutFrame);
 for (int i{ 0 }; i < bSize; i++) {
 pOutFrame->data[0][i] = convertedSamplesBuffer[0][i];
 cout << pOutFrame->data[0][i];
 }
 if (pOutFrame) {
 pOutFrame->pts = pts;
 pts += pOutFrame->nb_samples;
 }
 int res = avcodec_send_frame(pOutCodecCtx, pOutFrame);
 if (res < 0) {
 cout << "error sending frame to encoder" << endl;
 cleanUp();
 return -1;
 }
 //int er = avformat_write_header(pOutFormatCtx,nullptr);
 AVPacket* pOutPacket = av_packet_alloc();
 pOutPacket->time_base.num = 1;
 pOutPacket->time_base.den = 8000;
 if (pOutPacket == nullptr) {
 cout << "unable to allocate packet" << endl;
 }
 while (res >= 0) {
 res = avcodec_receive_packet(pOutCodecCtx, pOutPacket);
 if (res == AVERROR(EAGAIN))
 continue;
 else if (ret == AVERROR_EOF)
 break;
 av_packet_rescale_ts(pOutPacket, pOutCodecCtx->time_base, pOutFormatCtx->streams[0]->time_base);
 //av_dump_format(pOutFormatCtx, 0, outFilename.c_str(), 1);
 if (av_write_frame(pOutFormatCtx, pOutPacket) < 0) {
 cout << "could not write frame" << endl;
 }
 }
 }
}
 av_frame_free(&pFrame);
 av_frame_free(&pOutFrame);
}
if (av_write_trailer(pOutFormatCtx) < 0) {
 cout << "could not write file trailer" << endl;
}
swr_free(&swr);
avcodec_free_context(&pOutCodecCtx);
av_packet_free(&packet);
}
</iostream>

Error/Exception


The exception is thrown when I call


if (av_write_frame(pOutFormatCtx, pOutPacket) < 0) { cout << "could not write frame" << endl; }
I also called this line

//int er = avformat_write_header(pOutFormatCtx,nullptr);

to see if I will get an exception but it did not throw any exception.


I have spent weeks on this issue with no success.
My goal is to take any audio from a file an be able to resample it if need be, and transcode it to PCM_ALAW.
I will appreciate any help I can get.


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