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• lavu/pixdesc : handle xv30be in av_[read|write]_image_line

  4 décembre 2022, par Philip Langdale

  lavu/pixdesc : handle xv30be in av_read_image_line
  xv30be is an obnoxious format that I shouldn't have included in the
  
  first place. xv30 packs 3 10bit channels into 32bits and while our
  
  byte-oriented logic can handle Little Endian correctly, it cannot
  
  handle Big Endian. To avoid that, I marked xv30be as a bitstream
  
  format, but while that didn't produce FATE errors, it turns out that
  
  the existing read/write code silently produces incorrect results, which
  
  can be revealed via ubsan.
  In all likelyhood, the correct fix here is to remove the format. As
  
  this format is only used by Intel vaapi, it's only going to show up
  
  in LE form, so we could just drop the BE version. But I don't want to
  
  deal with creating a hole in the pixfmt list and all the weirdness that
  
  comes from that. Instead, I decided to write the correct read/write
  
  code for it.
  And that code isn't too bad, as long as it's specialised for this
  
  format, as the channels are all bit-aligned inside a 32bit word.
  

  • [DH] libavutil/pixdesc.c

• Can I use a text file's content to create a filtered list for ffmpeg ?

  20 octobre 2022, par Angel Lopez Jr

  I am attempting to make a CMD script that will

  


  

  1. Create a text file that lists file names followed by video codec (using ffprobe)

  


  2. Create a new text from the list so that any file with x265 codec is removed from the list (and formated as
file "*filepath*"

  


  3. Run ffmpeg on the edited list to transcode remaining files to x265.

  


  


  I have a script that does #1

  


  for /R %%f IN (*.mkv,*.avi,*.mp4,*.m2ts,*.mts,*.rm,*.m4v) do echo "%%f" >>Probe.txt & ffprobe -v error -hide_banner -of default=noprint_wrappers=0 -print_format flat  -select_streams v:0 -show_entries stream=codec_name "%%f" >>Probe.txt & echo.  >>Probe.txt


  


  which outputs

  


  


  "filepath"
  
streams.stream.0.codec_name="codec"

  


  "filepath"
  
streams.stream.0.codec_name="codec"

  


  


  and I have a script that will do #3

  


  for /R %%f IN (*.mkv,*.avi,*.mp4,*.m2ts,*.mts,*.rm,*.m4v) do ffmpeg -hide_banner -hwaccel_output_format qsv -i "%%f" -c:v libx265 -c:a ac3 -x265-params crf=25 "%%f.mkv"


  


  I am not sure if #2 is even possible though.

  


  End result of task 2 should be that in probe.txt, any line that has a
streams.stream.0.codec_name value of anything besides hevc will have the line immediately above it written to a new txt file with the word file in front.

  


  final goal is getting all three tasks to run under one batch file (each task running sequentially)

  


  Is there any help on what I am missing to be able to unify these and get #2 to happen

  


• ffmpeg : avfilter's anull says "Rematrix is needed between stereo and 0 channels but there is not enough information to do it"

  12 juillet 2017, par kuanyui

  I’m trying to write a transcoder according to FFMpeg’s official example with ffmpeg 3.2.4 (official prebuild Win32), and try to transcode a video with stereo audio stream source (from avformat’s dshow).

  In the example code, which passes anull into avfilter_graph_parse_ptr() for audio stream, and "time_base=1/44100:sample_rate=44100:sample_fmt=s16:channels=2:channel_layout=0x3" is passed into avfilter_graph_create_filter(), occurs error in the following avfilter_graph_config() :

  [auto-inserted scaler 0 @ 32f77600] w:iw h:ih flags:'bilinear' interl:0
  
  [Parsed_null_0 @ 2e9d79a0] auto-inserting filter 'auto-inserted scaler 0' between the filter 'in' and the filter 'Parsed_null_0'
  
  [swscaler @ 3331bfe0] deprecated pixel format used, make sure you did set range correctly
  
  [auto-inserted scaler 0 @ 32f77600] w:1920 h:1080 fmt:yuvj422p sar:1/1 -> w:1920 h:1080 fmt:yuv420p sar:1/1 flags:0x2
  
  [libmp3lame @ 2e90a360] Channel layout not specified
  
  [in @ 3866e8a0] tb:1/44100 samplefmt:s16 samplerate:44100 chlayout:0x3
  
  [Parsed_anull_0 @ 330e8820] auto-inserting filter 'auto-inserted resampler 0' between the filter 'in' and the filter 'Parsed_anull_0'
  
  [auto-inserted resampler 0 @ 330e8dc0] [SWR @ 3809b620] Rematrix is needed between stereo and 0 channels but there is not enough information to do it
  
  [auto-inserted resampler 0 @ 330e8dc0] Failed to configure output pad on auto-inserted resampler 0

  I’ve googled for days but didn’t find any clue for it. Doesn’t what anull do is only "Pass the audio source unchanged to the output", why libav want to resample stereo to 0 channel ? What’s going wrong ?