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• react-native-ffmpeg Unrecognized option 'preset'

  8 avril 2021, par Tommy Khumarga

  Below is my ffmpeg command :

  


  -y -i vidInput.mp4 -vcodec mpeg4 -b:v 1000k -b:a 48000 -preset ultrafast vidOutput.mp4

  


  And the result is :

  


  [Mon Jul 06 2020 20:42:08.171]  LOG      Unrecognized option 'preset'.
[Mon Jul 06 2020 20:42:08.172]  LOG      Error splitting the argument list:
[Mon Jul 06 2020 20:42:08.174]  LOG      Option not found


  


  Need advice...

  


• Detect frame with incorrect poc

  3 août 2018, par Анзор Гергов

  When I try to decode packet (using this function avcodec_decode_video2) sometimes I get corrupt (gray) frame. This error is obtained because of the missed frames. ffmpeg shoes the following errors to the log :

  [hevc @ 000000000379b680] Could not find ref with POC 43 [hevc @
  000000000379b1c0] Duplicate POC in a sequence : 17. [hevc @
  000000000379b1c0] Error parsing NAL unit #0.

  I wanted to solve this problem by strictly adjusting the context of the decoder using the following flags : AV_EF_EXPLODE and AV_EF_AGGRESSIVE. Unfortunatly it didn’t help, errors continue appear in log, but avcodec_decode_video2 gives away corrupt frame.

  AVCodecContext* context = avcodec_alloc_context3(codecId);
  
  avctx->flags2 |= AV_CODEC_FLAG2_FAST;
  
  
  
  // Known encoder's bugs handling.
  
  avctx->workaround_bugs = AV_EF_EXPLODE | AV_EF_AGGRESSIVE;
  
  avctx->err_recognition = 0;
  
  avctx->error_concealment = 0;
  
  
  
  // Threads.
  
  avctx->thread_count = 4;
  
  avctx->thread_type = FF_THREAD_FRAME;
  
  .....
  
  avcodec_decode_video2(avctx, picture, got_picture_ptr, avpkt);
  
  ....

  What do I need to do to ensure that corrupted frames are not repeated ? Maybe I need to configure the context a little differently ?

  P.S. you can see ffmpeg version in attachment

• How to save ffmpeg segmets to disk immediately with sub-second intervals ?

  20 octobre 2023, par amfast

  I'm trying to record video on a raspberry and have it save as much as possible (sub-second resolution) in case of a power cutoff.

  


  I use -f segment to save the encoded stream in 100ms segments with the hope that all but the interrupted (by power cutoff) segment will be saved in memory. Unfortunately, when cutting off power, all the destination files (output_0001.mp4, output_0002.mp4, ...) are created, but empty.

  


  To save the files to disk immediately, I added the -strftime 1 option that allows formatting the output filename as time. It seems weird that this is the (only ?) way to trigger immediate saving of files, but it works - untill I try to have segments smaller than 1 second. The problem seems to be that the format string %d, that previously added a sequence number in my output filenames, now represents "day" (i.e. date) and the smallest resolution time format string is %S for second. I saw %f suggested somewhere for smaller resolutions, but it only prints "%f".

  


  The result is that the segmentation part of ffmpeg does create 100ms segments and save them to disk immediately, but the strftime feature gives the output files names that only change every second, so all the interim files are overwritten.

  


  Example of the failing command below. Without the -strftime option this creates nice segments, but does not save them to disk immediately.

  


  libcamera-vid --flush \
    --framerate ${FRAMERATE} \
    --width ${WIDTH} \
    --height ${HEIGHT} \
    -n \
    -t ${TIMEOUT} \
    --codec yuv420 \
    -o - | 
ffmpeg \
    -fflags nobuffer \
    -strict experimental \
    -loglevel debug \
    -flags low_delay \
    -f rawvideo \
    -pix_fmt yuv420p \
    -s:v ${WIDTH}x${HEIGHT} \
    -r ${FRAMERATE} \
    -i - \
    -c:v h264_v4l2m2m \
    -f segment \
    -segment_time 0.1 \
    -segment_format mp4 \
    -reset_timestamps 1 \
    -strftime 1 \
    -b:v ${ENCODING_BITRATE} \
    -g 1 \
    "output_%04d.mp4"


  


  Question :
  
Is there another way besides -strftime to trigger immediate saving ? Or is there a mechanism to feed finer resolution format strings to the output filename ?