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• lavf : improve support for AVC-Intra files.

  26 septembre 2012, par Reimar Döffinger

  lavf : improve support for AVC-Intra files.
  Generate extradata with SPS/PPS based on container dimensions.
  Authors of this commit are : Reimar and Thomas Mundt
  Signed-off-by : Anton Khirnov <anton@khirnov.net>
  

  • [DBH] libavformat/internal.h
  • [DBH] libavformat/isom.c
  • [DBH] libavformat/isom.h
  • [DBH] libavformat/mov.c
  • [DBH] libavformat/mxfdec.c
  • [DBH] libavformat/utils.c

• avfilter : add a blend_vulkan filter

  31 décembre 2021, par Wu Jianhua

  avfilter : add a blend_vulkan filter
  This commit adds a blend_vulkan filter and a normal blend mode, and
  
  reserves support for introducing the blend modes in the future.
  Use the commands below to test : (href : https://trac.ffmpeg.org/wiki/Blend)
  
  I. make an image for test
  
  ffmpeg -f lavfi -i color=s=256x256,geq=r='H-1-Y':g='H-1-Y':b='H-1-Y' -frames 1 \
  
   y -pix_fmt yuv420p test.jpg
  II. blend in sw
  
  ffmpeg -i test.jpg -vf "split[a][b] ;[b]transpose[b] ;[a][b]blend=all_mode=normal,\
  
  pseudocolor=preset=turbo" -y normal_sw.jpg
  III. blend in vulkan
  
  ffmpeg -init_hw_device vulkan -i test.jpg -vf "split[a][b] ;[b]transpose[b] ;\
  
  [a]hwupload[a] ;[b]hwupload[b] ;[a][b]blend_vulkan=all_mode=normal,hwdownload,\
  
  format=yuv420p,pseudocolor=preset=turbo" -y normal_vulkan.jpg
  Signed-off-by : Wu Jianhua <jianhua.wu@intel.com>
  

  • [DH] configure
  • [DH] libavfilter/Makefile
  • [DH] libavfilter/allfilters.c
  • [DH] libavfilter/vf_blend_vulkan.c

• Python : Strange hanging behavior when piping large stdout of a subprocess

  7 septembre 2017, par Victor Odouard

  I am currently calling ffmpeg to extract a binary data stream from a video file, and then putting that binary data into a list. There is a lot of data in this data stream, about 4,000 kb. Here is the code

  # write and call ffmpeg command, piping stdout
  
  cmd = "ffmpeg -i video.mpg -map 0:1 -c copy -f data -"
  
  proc = subprocess.Popen(cmd, stdout=subprocess.PIPE)
  
  
  
  # read from stdout, byte by byte
  
  li = []
  
  for char in iter(lambda: proc.stdout.read(1), ""):
  
      li.append(char)

  This works fine. However, if I take out the part where I am reading from stdout, it starts working but then hangs :

  cmd = "ffmpeg -i video.mpg -map 0:1 -c copy -f data -"
  
  proc = subprocess.Popen(cmd, stdout=subprocess.PIPE)
  
  time.sleep(10)

  I had to add time.sleep(10) at the end or else the process would end before the subprocess, causing this error :

  av_interleaved_write_frame(): Invalid argument
  
  Error writing trailer of pipe:: Invalid argument
  
  size=       0kB time=00:00:00.00 bitrate=N/A speed=N/A
  
  video:0kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing ove
  
  rhead: 0.000000%
  
  Conversion failed!

  Calling either subprocess.call(cmd, stdout=subprocess.PIPE) or subprocess.call(cmd) also cause hanging (the latter just displays the stdout in the console while the former doesn’t).

  Is there something about reading from stdout that prevents this hanging (like perhaps the buffer getting cleared), or am I unknowingly introducing a bug elsewhere ? I’m worried that such a small change causes the program to break ; it doesn’t inspire very much confidence.

  The other issue with this code is that I need to read from the list from another thread. This might mean I need to use a Queue. But when I execute the below code, it takes 11 seconds as opposed to 3 seconds with the list equivalent :

  cmd = "ffmpeg -i video.mpg -loglevel panic -hide_banner -map 0:1 -c copy -f data -"
  
  proc = subprocess.Popen(cmd, stdout=subprocess.PIPE)
  
  
  
  q = Queue()
  
  
  
  for char in iter(lambda: proc.stdout.read(1), ""):
  
      q.put(char)

  Should I be using another data structure ?