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• How can I skip an image error when trimming an mp3 with ffmpeg

  29 septembre 2016, par John Pollard

  I am running the following command to get cut a 30 second section of the file

  ffmpeg -i 'river.mp3' -ss 30 -t 30 -acodec libmp3lame -b:a 128k 'audio_trimmed.mp3'

  but I am getting a "Invalid PNG signature" error. Is there a way to skip the image since I don’t need it and have the command run successfully ?

  ffmpeg version 2.8.5 Copyright (c) 2000-2016 the FFmpeg developers
  
    built with Apple LLVM version 7.3.0 (clang-703.0.31)
  
    configuration: --prefix=/usr/local/Cellar/ffmpeg/2.8.5 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-opencl --enable-libx264 --enable-libmp3lame --enable-libvo-aacenc --enable-libxvid --enable-libvorbis --enable-vda
  
    libavutil      54. 31.100 / 54. 31.100
  
    libavcodec     56. 60.100 / 56. 60.100
  
    libavformat    56. 40.101 / 56. 40.101
  
    libavdevice    56.  4.100 / 56.  4.100
  
    libavfilter     5. 40.101 /  5. 40.101
  
    libavresample   2.  1.  0 /  2.  1.  0
  
    libswscale      3.  1.101 /  3.  1.101
  
    libswresample   1.  2.101 /  1.  2.101
  
    libpostproc    53.  3.100 / 53.  3.100
  
  [mp3 @ 0x7f8419010600] Skipping 0 bytes of junk at 73436.
  
  [png @ 0x7f8419812600] Invalid PNG signature 0xFFD8FFE000104A46.
  
  [mp3 @ 0x7f8419010600] decoding for stream 1 failed
  
  [mp3 @ 0x7f8419010600] Could not find codec parameters for stream 1 (Video: png, none(pc)): unspecified size
  
  Consider increasing the value for the 'analyzeduration' and 'probesize' options
  
  Input #0, mp3, from 'river.mp3':
  
    Metadata:
  
      genre           : Podcast
  
      album           : River City Church's Podcast
  
      artist          : Antley Fowler
  
      title           : Jubilee Brings Justice
  
      date            : 2016-08-15 10:23
  
    Duration: 00:28:28.07, start: 0.025056, bitrate: 64 kb/s
  
      Stream #0:0: Audio: mp3, 44100 Hz, mono, s16p, 64 kb/s
  
      Stream #0:1: Video: png, none(pc), 90k tbr, 90k tbn, 90k tbc
  
      Metadata:
  
        title           : Episode Artwork
  
        comment         : Cover (front)
  
  [buffer @ 0x7f8418c18de0] Unable to parse option value "0x0" as image size
  
  [buffer @ 0x7f8418c18de0] Unable to parse option value "-1" as pixel format
  
  [buffer @ 0x7f8418c18de0] Unable to parse option value "0x0" as image size
  
  [buffer @ 0x7f8418c18de0] Error setting option video_size to value 0x0.
  
  [graph 0 input from stream 0:1 @ 0x7f8418c18ee0] Error applying options to the filter.
  
  Error opening filters!

• Does libavcodec provide a way to replace the video frames in an input, leaving the audio untouched ?

  25 février 2021, par Sniggerfardimungus

  I have a working project, congealed together using a number of examples, that extracts video frames from a .mp4, does some rendering over the top of them, then writes a new video with the new frames. The trouble is, I lose the audio in this process. When I add an avformat stream to the output video, I start getting cryptic crashes in mux.c::compute_muxer_pkt_fields, where st->internal->priv_pts is null.

  


  I've rather reinvented the wheel here - doing the full video decode and frame extraction, followed by writing my own code to create a new video. It seems that someone has to have taken care of the rather simple process of just extracting, then replacing every frame of a video. Alternatively, should I just junk all the code I've written and just use popen and the command-line ffmpeg to stream in and out the video frames, then use another popen call to copy the audio from the source video to the destination ? (like this)

  


  If no such beast exists, I'll see if I can't make enough sense of the mess that my code has become to get it posted.

  


• hdsenc : Clear the previous codec tag when setting up the chained muxer

  18 novembre 2014, par Martin Storsjö

  hdsenc : Clear the previous codec tag when setting up the chained muxer
  The chained flv muxer wants one set of tags - normally this set
  
  could be signaled via the AVOutputFormat codec_tag field (as
  
  smoothstreamingenc and dashenc do). hdsenc doesn’t signal it, since
  
  the FLV codec tag arrays aren’t exported from flvenc.c. This can
  
  lead to the caller keeping an original codec tag from the originating
  
  container here, which would then be a mismatch for the FLV muxer.
  
  Since we don’t really care about what codec tag the caller might
  
  have set, just clear it and let the lavf muxer layer set the right
  
  one for the chained FLV muxer later instead.
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] libavformat/hdsenc.c