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• Green tint color shift converting RGBA to YUV420p ffmpeg libavcodec

  2 août 2017, par Michael B

  I was wondering someone could help. I’m currently taking converting RBGA bitmaps to YUV420p before encoding the frames with h264 codec and dumping the encoded packets to file successfully.

  I’m also able to playback the h264 video file in VLC. However, there seems to be a color shift which is more apparent where grey is actually light tint of screen. I’m used a an animation video as my example which is supposed to show a blue sky in the background, however after converting the image, I’m getting an orange sky background. Do you have any ideas how I can fix this please ?

  Do you happen to know if it’s possible to convert rgba to yuv BEFORE calling sws_scale and before encoding packet ?

• Recording screencast using ffmpeg produces audio that is out of sync with the video

  7 décembre 2014, par AgilE

  I’m on Fedora 20. I got it pre-compiled from the repo.

  I use the follow command to record screencasts :

  ffmpeg -f alsa -ac 2 -i pulse -f x11grab -r 30 -s 1366x768 -i :0.0 -acodec pcm_s16le -vcodec libx264 -preset ultrafast -crf 0 -threads 0 filename.mkv

  The audio is perfectly synced with the video at the beginning. However, as the video progresses, the audio starts lagging behind severely (say a lag of more than 4 seconds). I’ve included a sample output that ffmpeg shows while recording a video.

  ffmpeg version 2.1.3 Copyright (c) 2000-2013 the FFmpeg developers
  
    built on Jan 25 2014 15:11:42 with gcc 4.8.2 (GCC) 20131212 (Red Hat 4.8.2-7)
  
    configuration: --prefix=/usr --bindir=/usr/bin --datadir=/usr/share/ffmpeg --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --arch=x86_64 --optflags='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic' --enable-bzlib --disable-crystalhd --enable-frei0r --enable-gnutls --enable-libass --enable-libcdio --enable-libcelt --enable-libdc1394 --disable-indev=jack --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-openal --enable-libopencv --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libv4l2 --enable-libvpx --enable-libx264 --enable-libxvid --enable-x11grab --enable-avfilter --enable-avresample --enable-postproc --enable-pthreads --disable-static --enable-shared --enable-gpl --disable-debug --disable-stripping --shlibdir=/usr/lib64 --enable-runtime-cpudetect
  
    libavutil      52. 48.101 / 52. 48.101
  
    libavcodec     55. 39.101 / 55. 39.101
  
    libavformat    55. 19.104 / 55. 19.104
  
    libavdevice    55.  5.100 / 55.  5.100
  
    libavfilter     3. 90.100 /  3. 90.100
  
    libavresample   1.  1.  0 /  1.  1.  0
  
    libswscale      2.  5.101 /  2.  5.101
  
    libswresample   0. 17.104 /  0. 17.104
  
    libpostproc    52.  3.100 / 52.  3.100
  
  Guessed Channel Layout for  Input Stream #0.0 : stereo
  
  Input #0, alsa, from 'pulse':
  
    Duration: N/A, start: 1391533629.323015, bitrate: 1536 kb/s
  
      Stream #0:0: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s
  
  [x11grab @ 0x153ad80] device: :0.0 -> display: :0.0 x: 0 y: 0 width: 1366 height: 768
  
  [x11grab @ 0x153ad80] shared memory extension found
  
  Input #1, x11grab, from ':0.0':
  
    Duration: N/A, start: 1391533629.365274, bitrate: 1007124 kb/s
  
      Stream #1:0: Video: rawvideo (BGR[0] / 0x524742), bgr0, 1366x768, 1007124 kb/s, 30 tbr, 1000k tbn, 30 tbc
  
  [swscaler @ 0x1520460] deprecated pixel format used, make sure you did set range correctly
  
  No pixel format specified, yuv444p for H.264 encoding chosen.
  
  Use -pix_fmt yuv420p for compatibility with outdated media players.
  
  [libx264 @ 0x1551420] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
  
  [libx264 @ 0x1551420] profile High 4:4:4 Predictive, level 3.2, 4:4:4 8-bit
  
  [libx264 @ 0x1551420] 264 - core 138 r2363 c628e3b - H.264/MPEG-4 AVC codec - Copyleft 2003-2013 - http://www.videolan.org/x264.html - options: cabac=0 ref=1 deblock=0:0:0 analyse=0:0 me=dia subme=0 psy=0 mixed_ref=0 me_range=16 chroma_me=1 trellis=0 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=0 chroma_qp_offset=0 threads=6 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=cqp mbtree=0 qp=0
  
  Output #0, matroska, to 'testing.mkv':
  
    Metadata:
  
      encoder         : Lavf55.19.104
  
      Stream #0:0: Video: h264 (libx264) (H264 / 0x34363248), yuv444p, 1366x768, q=-1--1, 1k tbn, 30 tbc
  
      Stream #0:1: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, stereo, s16, 1536 kb/s
  
  Stream mapping:
  
    Stream #1:0 -> #0:0 (rawvideo -> libx264)
  
    Stream #0:0 -> #0:1 (pcm_s16le -> pcm_s16le)
  
  Press [q] to stop, [?] for help
  
  [swscaler @ 0x1520460] Warning: data is not aligned! This can lead to a speedloss
  
  frame=  213 fps= 27 q=-1.0 Lsize=    3572kB time=00:00:08.00 bitrate=3653.6kbits/s    
  
  video:2025kB audio:1501kB subtitle:0 global headers:0kB muxing overhead 1.291094%
  
  [libx264 @ 0x1551420] frame I:1     Avg QP: 0.00  size:692585
  
  [libx264 @ 0x1551420] frame P:212   Avg QP: 0.00  size:  6509
  
  [libx264 @ 0x1551420] mb I  I16..4: 100.0%  0.0%  0.0%
  
  [libx264 @ 0x1551420] mb P  I16..4: 47.2%  0.0%  0.0%  P16..4:  0.1%  0.0%  0.0%  0.0%  0.0%    skip:52.8%
  
  [libx264 @ 0x1551420] coded y,u,v intra: 0.7% 0.7% 0.7% inter: 0.1% 0.1% 0.1%
  
  [libx264 @ 0x1551420] i16 v,h,dc,p: 100%  0%  0%  0%
  
  [libx264 @ 0x1551420] kb/s:2335.32

  Is there something I’m missing ?

• FFMPEG - Stream discovered after head already parsed [on hold]

  7 février 2014, par John Doe

  I am trying to live transcode an RTMP stream to another RTMP HLS stream using the following command :

  ffmpeg -re -i rtmp://localhost/videochat/testing -c:v libx264 -c:a:0 libfaac -b:a:0 480k -f flv rtmp://localhost:12345/hls/mystream;

  However I receive the following error and the transcoding never begins :

  ffmpeg version git-2014-02-06-474db7a Copyright (c) 2000-2014 the FFmpeg developers
  
  built on Feb  6 2014 22:20:14 with gcc 4.6 (Ubuntu/Linaro 4.6.3-1ubuntu5)
  
  configuration: --enable-gpl --enable-libass --enable-libfaac --enable-libfdk-aac --               enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-librtmp --enable-libtheora --enable-libvorbis --enable-libvpx --enable-x11grab --enable-libx264 --enable-nonfree --enable-version3
  
  libavutil      52. 63.100 / 52. 63.100
  
  libavcodec     55. 49.101 / 55. 49.101
  
  libavformat    55. 30.100 / 55. 30.100
  
  libavdevice    55.  7.100 / 55.  7.100
  
  libavfilter     4.  1.102 /  4.  1.102
  
  libswscale      2.  5.101 /  2.  5.101
  
  libswresample   0. 17.104 /  0. 17.104
  
  libpostproc    52.  3.100 / 52.  3.100
  
  Metadata:
  
  description           Chat using VideoChat example.
  
  [flv @ 0x1ec89e0] Stream discovered after head already parsed
  
  ^C[flv @ 0x1ec89e0] Could not find codec parameters for stream 0 (Video: none):    unspecified size
  
  Consider increasing the value for the 'analyzeduration' and 'probesize' options
  
  Input #0, flv, from 'rtmp://localhost/videochat/testing':
  
  Metadata:
  
  description     : Chat using VideoChat ex   ?5P
  
  Duration: N/A, start: 0.000000, bitrate: N/A
  
  Stream #0:0: Video: none, 1k tbr, 1k tbn, 1k tbc
  
  Stream #0:1: Data: none
  
  Codec AVOption b (set bitrate (in bits/s)) specified for output file #0 (rtmp://localhost:12345/hls/mystream) has not been used for any stream. The most likely reason is either wrong type (e.g. a video option with no video streams) or that it is a private option of some encoder which was not actually used for any stream.
  
  Output #0, flv, to 'rtmp://localhost:12345/hls/mystream':

  If anyone has ever dealt/solved this problem before, can you please share as I have been trying to solve this for 2 days but to no avail !