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Sur d’autres sites (6740)

  • ffmpeg mapping to mkv introduces "fake" delay relative to video

    1er août 2016, par JMor

    I need to map this x.264 clip into a matroska container using ffmpeg :

    ffmpeg -i f-0.mp4 -c copy f-0.mkv

    Here is the ffmpeg console output :

    ffmpeg -i f-0.mp4 -c copy f-0.mkv  
    ffmpeg version N-69672-g078be09 Copyright (c) 2000-2015 the FFmpeg developers
     built with gcc 4.9.2 (GCC)
     configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-lzma --enable-decklink --enable-zlib
     libavutil      54. 18.100 / 54. 18.100
     libavcodec     56. 21.102 / 56. 21.102
     libavformat    56. 19.100 / 56. 19.100
     libavdevice    56.  4.100 / 56.  4.100
     libavfilter     5.  9.104 /  5.  9.104
     libswscale      3.  1.101 /  3.  1.101
     libswresample   1.  1.100 /  1.  1.100
     libpostproc    53.  3.100 / 53.  3.100
    Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'f-0.mp4':
     Metadata:
       major_brand     : isom
       minor_version   : 512
       compatible_brands: isomiso2avc1mp41
       encoder         : Lavf56.19.100
     Duration: 00:02:08.06, start: 0.005333, bitrate: 5030 kb/s
       Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 4865 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 59.94 tbc (default)
       Metadata:
         handler_name    : VideoHandler
       Stream #0:1(und): Audio: ac3 (ac-3 / 0x332D6361), 48000 Hz, stereo, fltp, 160 kb/s (default)
       Metadata:
         handler_name    : SoundHandler
       Side data:
         unknown side data type 7 (4 bytes)
    Output #0, matroska, to 'f-0.mkv':
     Metadata:
       major_brand     : isom
       minor_version   : 512
       compatible_brands: isomiso2avc1mp41
       encoder         : Lavf56.19.100
       Stream #0:0(und): Video: h264 (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 4865 kb/s, 29.97 fps, 29.97 tbr, 1k tbn, 30k tbc (default)
       Metadata:
         handler_name    : VideoHandler
       Stream #0:1(und): Audio: ac3 ([0] [0][0] / 0x2000), 48000 Hz, stereo, 160 kb/s (default)
       Metadata:
         handler_name    : SoundHandler
       Side data:
         unknown side data type 7 (4 bytes)
    Stream mapping:
     Stream #0:0 -> #0:0 (copy)
     Stream #0:1 -> #0:1 (copy)
    ...

    The result seems good, playing with well synchronized audio and video. However, MediaInfo shows a new item under Audio (that the original clip didn’t have) :

    Delay relative to video                  : 1mn 5s

    Here is the Mediainfo from the original f-0.mp4 file :

    Audio
     ID                                       : 2
     Format                                   : AC-3
     Format/Info                              : Audio Coding 3
     Mode extension                           : CM (complete main)
     Format settings, Endianness              : Big
     Codec ID                                 : ac-3
     Duration                                 : 2mn 8s
     Bit rate mode                            : Constant
     Bit rate                                 : 160 Kbps
     Channel(s)                               : 2 channels
     Channel positions                        : Front: L R
     Sampling rate                            : 48.0 KHz
     Bit depth                                : 16 bits
     Compression mode                         : Lossy
     Delay relative to video                  : 67ms
     Stream size                              : 2.44 MiB (3%)

    Mediainfo from the f-0.mkv output :

    Audio
     ID                                       : 2
     Format                                   : AC-3
     Format/Info                              : Audio Coding 3
     Mode extension                           : CM (complete main)
     Format settings, Endianness              : Big
     Codec ID                                 : A_AC3
     Duration                                 : 2mn 8s
     Bit rate mode                            : Constant
     Bit rate                                 : 160 Kbps
     Channel(s)                               : 2 channels
     Channel positions                        : Front: L R
     Sampling rate                            : 48.0 KHz
     Bit depth                                : 16 bits
     Compression mode                         : Lossy
     Delay relative to video                  : 1mn 5s
     Stream size                              : 2.44 MiB (3%)
     Default                                  : Yes
     Forced                                   : No
     HANDLER_NAME                             : SoundHandler

    There is no delay whatsoever and no reason to insert a delay.

    I am concerned that this information (Delay relative to video) be used by some players or other applications as a delay that should be corrected. Is there a way to prevent this from happening ?

    Adding ffprobe output : f-0.mp4 clip

    ffprobe -show_entries stream=codec_type,duration,start_time -of compact f-0.mp4
       ffprobe version N-69672-g078be09 Copyright (c) 2007-2015 the FFmpeg developers
       built with gcc 4.9.2 (GCC)
       configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-lzma --enable-decklink --enable-zlib
       libavutil      54. 18.100 / 54. 18.100
       libavcodec     56. 21.102 / 56. 21.102
       libavformat    56. 19.100 / 56. 19.100
       libavdevice    56.  4.100 / 56.  4.100
       libavfilter     5.  9.104 /  5.  9.104
       libswscale      3.  1.101 /  3.  1.101
       libswresample   1.  1.100 /  1.  1.100
       libpostproc    53.  3.100 / 53.  3.100
     Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'f-0.mp4':
       Metadata:
         major_brand     : isom
         minor_version   : 512
         compatible_brands: isomiso2avc1mp41
         encoder         : Lavf56.19.100
       Duration: 00:02:08.06, start: 0.005333, bitrate: 5030 kb/s
         Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 4865 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 59.94 tbc (default)
         Metadata:
           handler_name    : VideoHandler
         Stream #0:1(und): Audio: ac3 (ac-3 / 0x332D6361), 48000 Hz, stereo, fltp, 160 kb/s (default)
         Metadata:
           handler_name    : SoundHandler
         Side data:
           unknown side data type 7 (4 bytes)
     stream|codec_type=video|start_time=0.000000|duration=128.061267
     stream|codec_type=audio|start_time=-0.005333|duration=128.064000

    f-0.mkv clip :

    ffprobe version N-69672-g078be09 Copyright (c) 2007-2015 the FFmpeg developers
     built with gcc 4.9.2 (GCC)
     configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-lzma --enable-decklink --enable-zlib
     libavutil      54. 18.100 / 54. 18.100
     libavcodec     56. 21.102 / 56. 21.102
     libavformat    56. 19.100 / 56. 19.100
     libavdevice    56.  4.100 / 56.  4.100
     libavfilter     5.  9.104 /  5.  9.104
     libswscale      3.  1.101 /  3.  1.101
     libswresample   1.  1.100 /  1.  1.100
     libpostproc    53.  3.100 / 53.  3.100
    Input #0, matroska,webm, from 'f-0.mkv':
     Metadata:
       COMPATIBLE_BRANDS: isomiso2avc1mp41
       MAJOR_BRAND     : isom
       MINOR_VERSION   : 512
       ENCODER         : Lavf56.19.100
     Duration: 00:02:08.13, start: 0.061000, bitrate: 5026 kb/s
       Stream #0:0(und): Video: h264 (High), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 29.97 fps, 29.97 tbr, 1k tbn, 59.94 tbc (default)
       Metadata:
         LANGUAGE        : und
         HANDLER_NAME    : VideoHandler
       Stream #0:1(und): Audio: ac3, 48000 Hz, stereo, fltp, 160 kb/s (default)
       Metadata:
         LANGUAGE        : und
         HANDLER_NAME    : SoundHandler
    stream|codec_type=video|start_time=0.066000|duration=N/A
    stream|codec_type=audio|start_time=0.061000|duration=N/A
  • Revision ec8864a8bf : Added MACRO for reference frame encoding This CL introduces a few macros plus c

    11 septembre 2015, par Zoe Liu

    Changed Paths :
     Modify /vp9/common/vp9_blockd.h


     Modify /vp9/common/vp9_entropymode.c


     Modify /vp9/common/vp9_entropymode.h


     Modify /vp9/common/vp9_pred_common.h


     Modify /vp9/decoder/vp9_decodeframe.c


     Modify /vp9/decoder/vp9_decodemv.c


     Modify /vp9/encoder/vp9_bitstream.c


     Modify /vp9/encoder/vp9_encodeframe.c



    Added MACRO for reference frame encoding

    This CL introduces a few macros plus code cleaning on the encoding of
    the reference frames. Coding performance remains unchanged.

    For the encoding of either the compound reference or the single reference
    case, since each bit has different contexts, the tree structure may not
    be applied to treat the combined bits as one symbol. It is possible we may
    explore the sharing of the same context for all the bits to introduce
    the use of tree structure for the next step.

    Change-Id : I6916ae53c66be1a0b23e6273811c0139515484df

  • Decode h264 stream with ffmpeg introduces a delay, how to avoid ?

    17 mai 2013, par Jonas Jongejan

    I'm working on some code that encodes a video feed, sends it over UDP to a client that then decodes the stream. It working fine using a x264 encoder, my only problem is that when i call avcodec_decode_video2 on the incomming frame, the decoder introduces a delay as if it has an internal buffer. How can i avoid this ? What is controlling this behavior ? Is it the encoder that should be changed, or is it missing settings in the decoder context ? Currently i just create the decoder context with defaults avcodec_get_context_defaults3.

    The encoder has the following parameters :

    x264_param_t param;
    x264_param_default_preset(&param, preset.c_str(), "zerolatency");
    param.i_frame_reference = 1;

    param.i_threads = 1;
    param.b_sliced_threads = 5;
    param.i_slice_max_size = 8192;
    param.i_width = width;
    param.i_height = height;
    param.i_fps_num = 30;
    param.i_fps_den = 1;
    param.i_sync_lookahead = 0;

    param.i_bframe = 0;
    // Intra refres:
    param.i_keyint_max = 30;
    param.b_intra_refresh = 1;
    //Rate control:
    param.rc.i_rc_method = X264_RC_CRF;
    param.rc.i_lookahead = 0;
    param.rc.i_bitrate = bitrate;
    param.rc.i_vbv_max_bitrate = bitrate;
    param.rc.i_vbv_buffer_size = bitrate/30;

    //For streaming:
    param.b_repeat_headers = 1;
    param.b_annexb = 1;