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• h264 inside AVI, MP4 and "Raw" h264 streams. Different format of NAL units

  6 octobre 2017, par bukkojot

  TL ;DR : I want to read raw h264 streams from AVI files, even broken/incomplete.

  Almost every document about h264 tells me that it consists of NAL packets. Okay. Almost everywhere told to me that the package should start with a signature like 00 00 01 or 00 00 00 01. For example, https://stackoverflow.com/a/18638298/8167678, https://stackoverflow.com/a/17625537/8167678

  The format of H.264 is that it’s made up of NAL Units, each starting
  with a start prefix of three bytes with the values 0x00, 0x00, 0x01
  and each unit has a different type depending on the value of the 4th
  byte right after these 3 starting bytes. One NAL Unit IS NOT one frame
  in the video, each frame is made up of a number of NAL Units.

  Okay.

  I downloaded random_youtube_video.mp4 and split one frame from it :

  ffmpeg -ss 10 -i random_youtube_video.mp4 -frames 1 -c copy pic.avi

  And got :
  
  Red part - this is part of AVI container, other - actual data.
  As you can see, here I have 00 00 24 A9 instead of 00 00 00 01

  This AVI file plays perfectly

  I do same for mp4 container :
  

  As you can see, here exact same bytes.
  This MP4 file plays perfectly

  I try to strip out raw data :
  ffmpeg -i pic.avi -c copy pic.h264
  

  This file can’t play in VLC or even ffmpeg, which produced this file, can’t parse it :
  

  I downloaded mp4 stream analyzer and got :
  

  MP4Box tells me :

   Cannot find H264 start code
  
   Error importing pic.h264: BitStream Not Compliant

  It very hard to learn internals of h264, when nothing works.

  So, I have questions :

  1. What actual data inside mp4 ?
  2. What I must read to decode that data (I mean different annex-es)
  3. How to read image and get decoded image (even with ffmpeg) from this "broken" raw stream ?

  UPDATE :

  It seems bug in ffmpeg :

  When I do double conversion :

           ffmpeg -ss 10 -i random_youtube_video.mp4 -frames 1 -c copy pic.mp4
  
           ffmpeg pic.mp4 -c copy pic.h264

  

  But when I convert file directly :

  ffmpeg -ss 10 -i random_youtube_video.mp4 -frames 1 -c copy pic.h264
  

  I have NALs signatures and one extra NAL unit. Other bytes are same (selected).

  This is bug ?

• FFMPEG : RTSP to HLS restream stops with "No more output streams to write to, finishing."

  1er juin 2022, par Tim W

  I'm trying to do a live restream an RTSP feed from a webcam using ffmpeg, but the stream repeatedly stops with the error :

  



  "No more output streams to write to, finishing."

  



  The problem seems to get worse at higher bitrates (256kbps is mostly reliable) and is pretty random in its occurrence. At 1mbps, sometimes the stream will run for several hours without any trouble, on other occasions the stream will fail every few minutes. I've got a cron job running which restarts the stream automatically when it fails, but I would prefer to avoid the continued interruptions.

  



  I have seen this problem reported in a handful of other forums, so this is not a unique problem, but not one of those reports had a solution attached to it. My ffmpeg command looks like this :

  



  ffmpeg -loglevel verbose -r 25 -rtsp_transport tcp -i rtsp ://user:password@camera.url/live/ch0 -reset_timestamps 1 -movflags frag_keyframe+empty_moov -bufsize 7168k -stimeout 60000 -hls_flags temp_file -hls_time 5 -hls_wrap 180 -acodec copy -vcodec copy streaming.m3u8 > encode.log 2>&1

  



  What gets me is that the error makes no sense, this is a live stream so output is always wanted until I shut off the stream. So having it shut down because output isn't wanted is downright odd. If ffmpeg was complaining because of a problem with input it would make more sense.

  



  I'm running version 3.3.4, which I believe is the latest.

  



  Update 13 Oct 17 :

  



  After extensive testing I've established that "No more outputs" error message generated by FFMPEG is very misleading. The error seems to be generated if the data coming in from RTSP is delayed, eg by other activity on the router the camera is connected via. I've got a large buffer and timeout set which should be sufficient for 60 seconds, but I can still deliberately trigger this error with far shorter interruptions, so clearly the buffer and timeout aren't having the desired effect. This might be fixed by setting a QOS policy on the router and by checking that the TCP packets from the camera have a suitably high priority set, it's possible this isn't the case.

  



  However, I would still like to improve the robustness of the input stream if it is briefly interrupted. Is there any way to persuade FFMPEG to tolerate this or to actually make use of the buffer it seems to be ignoring ? Can FFMPEG be persuaded to simply stop writing output and wait for input to become available rather than bailing out ? Or could I get FFMPEG to duplicate the last complete frame until it's able to get more data ? I can live with the stream stuttering a bit, but I've got to significantly reduce the current behaviour where the stream drops at the slightest hint of a problem.

  



  Further update 13 Oct 2017 :

  



  After more tests, I've found that the problem actually seems to be that HLS is incapable of coping with a discontinuity in the incoming video stream. If I deliberately cut the network connection between the camera and FFMPEG, FFMPEG will wait for the connection to be re-established for quite a long time. If the interruption was long (>10 seconds) the stream will immediately drop with the "No More Outputs" error the instant that the connection is re-established. If the interruption is short, then RTSP will actually start pulling data from the camera again, but the stream will then drop with the same error a few seconds later. So it seems clear that the gap in the input data is causing the HLS encoder to have a fit and give up once the stream is resumed, but the size of the gap has an impact on whether the drop is instant or not.

  


• 12 ffmpeg xfade transitions : "option not found"

  17 juillet 2023, par nimda

  I'm running into a strange error where each of these following 12 of the 56 xfade transitions are throwing errors :

  


  

  • hlwind

  


  • hrwind

  


  • vuwind

  


  • vdwind

  


  • coverleft

  


  • coverright

  


  • coverup

  


  • coverdown

  


  • revealleft

  


  • revealright

  


  • revealup

  


  • revealdown

  


  


  I've tested all filter transitions with the following command, which is being generated by a nodeJS app with the fluent-ffmpeg library, and only the twelve listed above fail with the same error "option not found" :

  


  ffmpeg -f lavfi -t 169
  -i color=c=000000:s=960x540:r=30:duration=169
  -i file:///Users/johnbandy/Work/Projects/Active/CNCT/XFade/_assets/crosstrekvx-1.jpg
  -i file:///Users/johnbandy/Work/Projects/Active/CNCT/XFade/_assets/crosstrekvx-2.jpg 
  -filter_complex
    [1:v]format=pix_fmts=yuva420p,scale=w=4608:h=-1,zoompan=z='1.2+(0*(ot/4))':x='(on/(30*4))*(iw-iw/1.2)':y='(ih-ih/zoom)/2':d=120:s=960x540[1_up];
    [1_up]scale=w=960:h=-1[1_down];
    [2:v]format=pix_fmts=yuva420p,scale=w=4608:h=-1,zoompan=z='1.2+(0*(ot/4))':x='(on/(30*4))*(iw-iw/1.2)':y='(ih-ih/zoom)/2':d=120:s=960x540[2_up];
    [2_up]scale=w=960:h=-1[2_down];
    [1_down][2_down]xfade=transition=revealdown:duration=1:offset=3[2_out];
    [0:v][2_out]overlay=x=0:y=0:enable='lte(t,7)'[all_out]
  -vcodec libx264 -r 30 -f mp4 -map [all_out] -preset veryfast -crf 18 -movflags frag_keyframe+empty_moov -pix_fmt yuv420p all.mp4


  


  fflog output :

  


  ffmpeg version 6.0 Copyright (c) 2000-2023 the FFmpeg developers
  built with Apple clang version 14.0.3 (clang-1403.0.22.14.1)
  configuration: --prefix=/opt/homebrew/Cellar/ffmpeg/6.0 --enable-shared --enable-pthreads --enable-version3 --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libaribb24 --enable-libbluray --enable-libdav1d --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librist --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libsvtav1 --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libspeex --enable-libsoxr --enable-libzmq --enable-libzimg --disable-libjack --disable-indev=jack --enable-videotoolbox --enable-audiotoolbox --enable-neon
  libavutil      58.  2.100 / 58.  2.100
  libavcodec     60.  3.100 / 60.  3.100
  libavformat    60.  3.100 / 60.  3.100
  libavdevice    60.  1.100 / 60.  1.100
  libavfilter     9.  3.100 /  9.  3.100
  libswscale      7.  1.100 /  7.  1.100
  libswresample   4. 10.100 /  4. 10.100
  libpostproc    57.  1.100 / 57.  1.100
Input #0, lavfi, from 'color=c=000000:s=960x540:r=30:duration=169':
  Duration: N/A, start: 0.000000, bitrate: N/A
  Stream #0:0: Video: wrapped_avframe, yuv420p, 960x540 [SAR 1:1 DAR 16:9], 30 fps, 30 tbr, 30 tbn
Input #1, image2, from 'file:///Users/johnbandy/Work/Projects/Active/CNCT/XFade/_assets/crosstrekvx-1.jpg':
  Duration: 00:00:00.04, start: 0.000000, bitrate: 36486 kb/s
  Stream #1:0: Video: mjpeg (Baseline), yuvj444p(pc, bt470bg/unknown/unknown), 960x540, 25 fps, 25 tbr, 25 tbn
Input #2, image2, from 'file:///Users/johnbandy/Work/Projects/Active/CNCT/XFade/_assets/crosstrekvx-2.jpg':
  Duration: 00:00:00.04, start: 0.000000, bitrate: 35680 kb/s
  Stream #2:0: Video: mjpeg (Baseline), yuvj444p(pc, bt470bg/unknown/unknown), 960x540, 25 fps, 25 tbr, 25 tbn
[Parsed_xfade_8 @ 0x60000137cb00] [Eval @ 0x16f9b5348] Undefined constant or missing '(' in 'revealdown'
[Parsed_xfade_8 @ 0x60000137cb00] Unable to parse option value "revealdown"
Error applying option 'transition' to filter 'xfade': Option not found
Error initializing complex filters.
Option not found


  


  The fflog for a successful video generation follows (for comparison to the erroneous log above) :

  


  ffmpeg version 6.0 Copyright (c) 2000-2023 the FFmpeg developers
  built with Apple clang version 14.0.3 (clang-1403.0.22.14.1)
  configuration: --prefix=/opt/homebrew/Cellar/ffmpeg/6.0 --enable-shared --enable-pthreads --enable-version3 --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libaribb24 --enable-libbluray --enable-libdav1d --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librist --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libsvtav1 --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libspeex --enable-libsoxr --enable-libzmq --enable-libzimg --disable-libjack --disable-indev=jack --enable-videotoolbox --enable-audiotoolbox --enable-neon
  libavutil      58.  2.100 / 58.  2.100
  libavcodec     60.  3.100 / 60.  3.100
  libavformat    60.  3.100 / 60.  3.100
  libavdevice    60.  1.100 / 60.  1.100
  libavfilter     9.  3.100 /  9.  3.100
  libswscale      7.  1.100 /  7.  1.100
  libswresample   4. 10.100 /  4. 10.100
  libpostproc    57.  1.100 / 57.  1.100
Input #0, lavfi, from 'color=c=000000:s=960x540:r=30:duration=169':
  Duration: N/A, start: 0.000000, bitrate: N/A
  Stream #0:0: Video: wrapped_avframe, yuv420p, 960x540 [SAR 1:1 DAR 16:9], 30 fps, 30 tbr, 30 tbn
Input #1, image2, from 'file:///Users/johnbandy/Work/Projects/Active/CNCT/XFade/_assets/crosstrekvx-1.jpg':
  Duration: 00:00:00.04, start: 0.000000, bitrate: 36486 kb/s
  Stream #1:0: Video: mjpeg (Baseline), yuvj444p(pc, bt470bg/unknown/unknown), 960x540, 25 fps, 25 tbr, 25 tbn
Input #2, image2, from 'file:///Users/johnbandy/Work/Projects/Active/CNCT/XFade/_assets/crosstrekvx-2.jpg':
  Duration: 00:00:00.04, start: 0.000000, bitrate: 35680 kb/s
  Stream #2:0: Video: mjpeg (Baseline), yuvj444p(pc, bt470bg/unknown/unknown), 960x540, 25 fps, 25 tbr, 25 tbn
Stream mapping:
  Stream #0:0 (wrapped_avframe) -> overlay
  Stream #1:0 (mjpeg) -> format:default
  Stream #2:0 (mjpeg) -> format:default
  overlay:default -> Stream #0:0 (libx264)
Press [q] to stop, [?] for help
[swscaler @ 0x140158000] deprecated pixel format used, make sure you did set range correctly
[swscaler @ 0x120098000] deprecated pixel format used, make sure you did set range correctly
[swscaler @ 0x130078000] deprecated pixel format used, make sure you did set range correctly
    Last message repeated 2 times
[swscaler @ 0x140598000] deprecated pixel format used, make sure you did set range correctly
[swscaler @ 0x1302d8000] deprecated pixel format used, make sure you did set range correctly
    Last message repeated 1 times
[libx264 @ 0x138e09080] using SAR=1/1
[libx264 @ 0x138e09080] using cpu capabilities: ARMv8 NEON
[libx264 @ 0x138e09080] profile High, level 3.1, 4:2:0, 8-bit
[libx264 @ 0x138e09080] 264 - core 164 r3095 baee400 - H.264/MPEG-4 AVC codec - Copyleft 2003-2022 - http://www.videolan.org/x264.html - options: cabac=1 ref=1 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=2 psy=1 psy_rd=1.00:0.00 mixed_ref=0 me_range=16 chroma_me=1 trellis=0 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=0 threads=12 lookahead_threads=4 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=1 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=10 rc=crf mbtree=1 crf=18.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
Output #0, mp4, to 'all.mp4':
  Metadata:
    encoder         : Lavf60.3.100
  Stream #0:0: Video: h264 (avc1 / 0x31637661), yuv420p(progressive), 960x540 [SAR 1:1 DAR 16:9], q=2-31, 30 fps, 15360 tbn
    Metadata:
      encoder         : Lavc60.3.100 libx264
    Side data:
      cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
frame=    0 fps=0.0 q=0.0 size=       0kB time=-577014:32:22.77 bitrate=  -0.0kbits/s speed=N/A    
frame=   32 fps=0.0 q=24.0 size=       0kB time=00:00:01.00 bitrate=   0.3kbits/s speed=1.94x    
frame=   87 fps= 84 q=24.0 size=       0kB time=00:00:02.83 bitrate=   0.1kbits/s speed=2.75x    
frame=  164 fps=107 q=24.0 size=       0kB time=00:00:05.40 bitrate=   0.1kbits/s speed=3.52x    
frame=  812 fps=399 q=24.0 size=     512kB time=00:00:26.96 bitrate= 155.5kbits/s speed=13.3x    
frame= 1821 fps=718 q=24.0 size=     512kB time=00:01:00.60 bitrate=  69.2kbits/s speed=23.9x    
frame= 2469 fps=813 q=24.0 size=     512kB time=00:01:22.23 bitrate=  51.0kbits/s speed=27.1x    
frame= 3421 fps=967 q=24.0 size=     512kB time=00:01:53.96 bitrate=  36.8kbits/s speed=32.2x    
frame= 4522 fps=1120 q=24.0 size=     768kB time=00:02:30.63 bitrate=  41.8kbits/s speed=37.3x    
frame= 5070 fps=1184 q=-1.0 Lsize=     812kB time=00:02:48.90 bitrate=  39.4kbits/s speed=39.5x    
video:769kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 5.626653%
[libx264 @ 0x138e09080] frame I:21    Avg QP: 2.73  size:  3710
[libx264 @ 0x138e09080] frame P:1305  Avg QP: 6.83  size:   449
[libx264 @ 0x138e09080] frame B:3744  Avg QP: 9.07  size:    33
[libx264 @ 0x138e09080] consecutive B-frames:  1.1%  1.4%  0.0% 97.5%
[libx264 @ 0x138e09080] mb I  I16..4: 95.4%  0.7%  3.8%
[libx264 @ 0x138e09080] mb P  I16..4:  0.1%  0.3%  0.1%  P16..4:  2.3%  0.2%  0.1%  0.0%  0.0%    skip:97.0%
[libx264 @ 0x138e09080] mb B  I16..4:  0.0%  0.0%  0.0%  B16..8:  0.1%  0.0%  0.0%  direct: 0.1%  skip:99.8%  L0:70.9% L1:27.3% BI: 1.8%
[libx264 @ 0x138e09080] 8x8 transform intra:13.8% inter:71.9%
[libx264 @ 0x138e09080] coded y,uvDC,uvAC intra: 19.1% 12.6% 5.2% inter: 0.3% 0.5% 0.0%
[libx264 @ 0x138e09080] i16 v,h,dc,p: 94%  2%  4%  1%
[libx264 @ 0x138e09080] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu:  7% 41% 22%  2%  6%  2%  9%  3%  8%
[libx264 @ 0x138e09080] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 11% 32% 16%  2% 11%  4% 12%  3%  8%
[libx264 @ 0x138e09080] i8c dc,h,v,p: 88%  9%  2%  1%
[libx264 @ 0x138e09080] Weighted P-Frames: Y:1.6% UV:1.6%
[libx264 @ 0x138e09080] kb/s:37.25