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• How do I toggle individual codec options in libavcodec (specifically h264_options)

  2 juillet 2020, par John Allard

  I'm trying to figure out how to enable enable_er option as is defined in h264dec.c in libavcodec. This is defined as an AVOption as part of the AVCodec.priv_class.option field. I can't figure out if this is some sort of compile-time option or if it's an option that I can enable via the av_dict_set method when initializing an AVCodec via avcodec_open2.

  


  I'm talking about these options in h264dec.c

  


  #define OFFSET(x) offsetof(H264Context, x)
#define VD AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_DECODING_PARAM
static const AVOption h264_options[] = {
    { "is_avc", "is avc", OFFSET(is_avc), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, 0 },
    { "nal_length_size", "nal_length_size", OFFSET(nal_length_size), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 4, 0 },
    { "enable_er", "Enable error resilience on damaged frames (unsafe)", OFFSET(enable_er), AV_OPT_TYPE_BOOL, { .i64 = -1 }, -1, 1, VD },
    { NULL },
};

static const AVClass h264_class = {
    .class_name = "H264 Decoder",
    .item_name  = av_default_item_name,
    .option     = h264_options,
    .version    = LIBAVUTIL_VERSION_INT,
};

AVCodec ff_h264_decoder = {
    .name                  = "h264",
    .long_name             = NULL_IF_CONFIG_SMALL("H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10"),
    .type                  = AVMEDIA_TYPE_VIDEO,
    .id                    = AV_CODEC_ID_H264,
    .priv_data_size        = sizeof(H264Context),
    .init                  = h264_decode_init,
    .close                 = h264_decode_end,
    .decode                = h264_decode_frame,
    .capabilities          = /*AV_CODEC_CAP_DRAW_HORIZ_BAND |*/ AV_CODEC_CAP_DR1 |
                             AV_CODEC_CAP_DELAY | AV_CODEC_CAP_SLICE_THREADS |
                             AV_CODEC_CAP_FRAME_THREADS,
    .caps_internal         = FF_CODEC_CAP_INIT_THREADSAFE | FF_CODEC_CAP_EXPORTS_CROPPING,
    .flush                 = flush_dpb,
    .init_thread_copy      = ONLY_IF_THREADS_ENABLED(decode_init_thread_copy),
    .update_thread_context = ONLY_IF_THREADS_ENABLED(ff_h264_update_thread_context),
    .profiles              = NULL_IF_CONFIG_SMALL(ff_h264_profiles),
    .priv_class            = &h264_class,
};


  


• How to use FFmpeg Colorspace Options

  13 octobre 2024, par Matt McManis

  I'm trying to understand the difference between Colorspace FFmpeg arguments :

  


  

  • Normal option, -colorspace bt709

  


  • Number, -colorspace 1

  


  • Codec Params -x264-params "colorspace=bt709"

  


  • Filter -vf "colorspace=bt709"

  


  


  The Colorspace categories are :

  


  

  • all

  


  • iall

  


  • colorspace

  


  • transfer

  


  • primaries

  


  • color range

  


  • color matrix

  


  


  ---

  


  Question

  


  When should each be used when encoding from raw, or transcoding/converting from one format to another ? Such as mpg to mp4.

  


  Do I need to specify the input colorspace or will FFmpeg auto-detect ?

  


  ---

  


  Problems

  


  There is no -vp8-params, only -x264-params. Should I use normal options or -vf instead for vp8 and other codecs ?

  


  ---

  


  Errors

  


  


  • There are no Normal -all or -colormatrix options, but there are all= and colormatrix= for -x264-params and -vf.

    


  


  • With Codec Params -x264-params "colorspace=bt709", I get Error parsing option 'colorspace = bt709'.
    
However colorprim=bt709, transfer=bt709, colormatrix=bt709 all work.

    


  


  


  ---

  


  Resources

  


  https://ffmpeg.org/ffmpeg-filters.html#colormatrix
  
https://ffmpeg.org/ffmpeg-filters.html#colorspace
  
https://trac.ffmpeg.org/wiki/colorspace

  


• What are supported ffmpeg rtp_mpegts Muxer options ? (mpegts Muxer options are ignored)

  7 mars 2020, par drake7

  I created a UDP stream with -f mpegts and some options like -mpegts_transport_stream_id.

  I received the stream with "StreamXpert - Real-time stream analyzer" that shows all options are in the output. See my ffmpeg parameters and the StreamXpert at the end.

  The same Muxer options seem to be ignored with -f rtp_mpegts.

  I have tried to use -f mpegts and pipe it to -f rtp_mpegts like so :

  ffmpeg -i ... -f mpegts pipe: | ffmpeg pipe: -c copy -f rtp_mpegts "rtp://239.1.1.9:1234?pkt_size=1316"

  The options are still ignored.

  This ticket "support options for MPEGTS muxer when using RTP_MPEGTS" also notices the ignored option. Furthermore in this comment, "thovo" gives an analysis and suggests a solution.

  Obviously the problem still exists. Anybody found a workaround for this ?

  My additional question : I have not questioned if my project really needs rtp in the first place. Maybe my coworker didn’t know better and requested rtp when udp would be sufficient as well.

  The aim was to receive the RTP stream with a TV using DVB via IP. This was successful an a Panasonic TV.

  The SAT>IP Specification on page 10 requires rtp for Media Transport :

  The SAT>IP protocol makes use of :

  • UPnP for Addressing, Discovery and Description,
  • RTSP or HTTP for Control,
  • RTP or HTTP for Media Transport.

  Is udp out of the equation ?

  ---

  ffmpeg : (all options are in the output with -f mpegts)

  (HEX to decimal : 0x005A = 90, 0x005B = 91 0x005C = 92, 0x005D = 93, 0x005E= 94)

  ffmpeg -f lavfi -i testsrc \
  
  -r 25 \
  
  -c:v libx264 \
  
  -pix_fmt yuv420p \
  
  -profile:v main -level 3.1 \
  
  -preset veryfast \
  
  -vf scale=1280:720,setdar=dar=16/9 \
  
  -an \
  
  -bsf:v h264_mp4toannexb \
  
  -flush_packets 0 \
  
  -b:v 4M \
  
  -muxrate 8M \
  
  -pcr_period 20 \
  
  -pat_period 0.10 \
  
  -sdt_period 0.25 \
  
  -metadata:s:a:0 language=nya \
  
  -mpegts_flags +pat_pmt_at_frames \
  
  -mpegts_transport_stream_id 0x005A \
  
  -mpegts_original_network_id 0x005B \
  
  -mpegts_service_id 0x005C \
  
  -mpegts_pmt_start_pid 0x005D \
  
  -mpegts_start_pid 0x005E \
  
  -mpegts_service_type advanced_codec_digital_hdtv \
  
  -metadata service_provider='WI' \ 
  
  -metadata service_name='W' \
  
  -mpegts_flags system_b -flush_packets 0 \
  
  -f mpegts "udp://239.1.1.10:1234?pkt_size=1316"

  StreamXpert Output :

  -mpegts_transport_stream_id = Transport Stream ID (yellow text highlight)

  -mpegts_original_network_id = Original Network ID, onw (green text highlight)

  -mpegts_service_id = Program, service (pink text highlight)

  -mpegts_pmt_start_pid = PMT PID, Table PID (turquoise text highlight)

  -mpegts_start_pid = PID, PCR PID (red text highlight)

  -mpegts_service_type = service type (blue text)

  service_name = Service name (orange text)

  service_provider = Service provider (pink text)