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• Revision 6ce718eb18 : Merge "End of orientation zero group experiment" into experimental

  22 avril 2013, par Deb Mukherjee

  Changed Paths : Modify /vp9/decoder/vp9_decodframe.c Modify /vp9/encoder/vp9_encodemb.c Modify /vp9/encoder/vp9_rdopt.c Merge "End of orientation zero group experiment" into experimental

• How to dump ALL metadata from a media file, including cover image title ? [closed]

  9 avril, par Unideal

  I have an MP3 song :

  


  # ffprobe -hide_banner -i filename.mp3
Input #0, mp3, from 'filename.mp3':
  Metadata:
    composer        : Music Author
    title           : Song Name
    artist          : Singer
    encoder         : Lavf61.7.100
    genre           : Rock
    date            : 2025
  Duration: 00:03:14.04, start: 0.023021, bitrate: 208 kb/s
  Stream #0:0: Audio: mp3 (mp3float), 48000 Hz, stereo, fltp, 192 kb/s
      Metadata:
        encoder         : Lavc61.19
  Stream #0:1: Video: png, rgb24(pc, gbr/unknown/unknown), 600x600 [SAR 1:1 DAR 1:1], 90k tbr, 90k tbn (attached pic)
      Metadata:
        title           : Cover
        comment         : Cover (front)


  


  The task is to save its metadata to a text file and restore from that file later. Both goals should be accomplished with ffmpeg.

  


  The simpliest method is to run :

  


  # ffmpeg -i filename.mp3 -f ffmetadata metadata.txt


  


  After that, metadata.txt contains :

  


  ;FFMETADATA1
composer=Music Author
title=Song Name
artist=Singer
date=2025
genre=Rock
encoder=Lavf61.7.100


  


  I got global metadata only, but stream-specific info (cover image title and comment in my case) are missing.

  


  Google suggested a more complex form of the command above to extract all metadata fields without any exclusions :

  


  # ffmpeg -y -i filename.mp3 -c copy -map_metadata 0 -map_metadata:s:v 0:s:v -map_metadata:s:a 0:s:a -f ffmetadata metadata.txt


  


  But the output is exactly the same :

  


  ;FFMETADATA1
composer=Music Author
title=Song Name
artist=Singer
date=2025
genre=Rock
encoder=Lavf61.7.100


  


  Again, no info about the attached image.

  


  Please explain what am I doing wrong.

  


• How to set pts, dts and duration in ffmpeg library ?

  24 mars, par hslee

  I want to pack some compressed video packets(h.264) to ".mp4" container.
One word, Muxing, no decoding and no encoding.
And I have no idea how to set pts, dts and duration.

  



  

  1. I get the packets with "pcap" library.

  


  2. I removed headers before compressed video data show up. e.g. Ethernet, VLAN.

  


  3. I collected data until one frame and decoded it for getting information of data. e.g. width, height. (I am not sure that it is necessary)

  


  4. I initialized output context, stream and codec context.

  


  5. I started to receive packets with "pcap" library again. (now for muxing)

  


  6. I made one frame and put that data in AVPacket structure.

  


  7. I try to set PTS, DTS and duration. (I think here is wrong part, not sure though)

  


  



  *7-1. At the first frame, I saved time(msec) with packet header structure.

  



  *7-2. whenever I made one frame, I set parameters like this : PTS(current time - start time), DTS(same PTS value), duration(current PTS - before PTS)

  



  I think it has some error because :

  



  


  1. I don't know how far is suitable long for dts from pts.

  


  2. At least, I think duration means how long time show this frame from now to next frame, so It should have value(next PTS - current PTS), but I can not know the value next PTS at that time.

  


  



  It has I-frame only.

  



  // make input context for decoding

AVFormatContext *&ic = gInputContext;

ic = avformat_alloc_context();

AVCodec *cd = avcodec_find_decoder(AV_CODEC_ID_H264);

AVStream *st = avformat_new_stream(ic, cd);

AVCodecContext *cc = st->codec;

avcodec_open2(cc, cd, NULL);

// make packet and decode it after collect packets is be one frame

gPacket.stream_index = 0;

gPacket.size    = gPacketLength[0];

gPacket.data    = gPacketData[0];

gPacket.pts     = AV_NOPTS_VALUE;

gPacket.dts     = AV_NOPTS_VALUE;

gPacket.flags   = AV_PKT_FLAG_KEY;

avcodec_decode_video2(cc, gFrame, &got_picture, &gPacket);

// I checked automatically it initialized after "avcodec_decode_video2"

// put some info that I know that not initialized

cc->time_base.den   = 90000;

cc->time_base.num   = 1;

cc->bit_rate    = 2500000;

cc->gop_size    = 1;

// make output context with input context

AVFormatContext *&oc = gOutputContext;

avformat_alloc_output_context2(&oc, NULL, NULL, filename);

AVFormatContext *&ic = gInputContext;

AVStream *ist = ic->streams[0];

AVCodecContext *&icc = ist->codec;

AVStream *ost = avformat_new_stream(oc, icc->codec);

AVCodecContext *occ = ost->codec;

avcodec_copy_context(occ, icc);

occ->flags |= CODEC_FLAG_GLOBAL_HEADER;

avio_open(&(oc->pb), filename, AVIO_FLAG_WRITE);

// repeated part for muxing

AVRational Millisecond = { 1, 1000 };

gPacket.stream_index = 0;

gPacket.data = gPacketData[0];

gPacket.size = gPacketLength[0];

gPacket.pts = av_rescale_rnd(pkthdr->ts.tv_sec * 1000 /

    + pkthdr->ts.tv_usec / 1000 /

    - gStartTime, Millisecond.den, ost->time_base.den, /

    (AVRounding)(AV_ROUND_NEAR_INF | AV_ROUND_PASS_MINMAX));

gPacket.dts = gPacket.pts;

gPacket.duration = gPacket.pts - gPrev;

gPacket.flags = AV_PKT_FLAG_KEY;

gPrev = gPacket.pts;

av_interleaved_write_frame(gOutputContext, &gPacket);


  



  Expected and actual results is a .mp4 video file that can play.