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• FFMPEG Transcode H265 video from 10-bit to 8-bit

  6 juin 2020, par Zach

  I'm trying to convert my library from various formats into HEVC 8-bit mainly to shrink my library down. This is generally working but I've run into an issue when trying to convert an existing file from 10-bit H.265 to 8-bit H.265.

  



  My processor, an Intel Celeron J3455, supports hardware decoding/encoding H.265 at 8-bit but only hardware decoding for 10-bit.

  



  It seems that ffmpeg is attempting to keep the video as 10-bit to match the source rather than allowing me to convert to 8-bit and this is creating an error.

  



  Here is a sample command that I'm using :

  



  ffmpeg -hwaccel vaapi -hwaccel_device /dev/dri/renderD128 -hwaccel_output_format vaapi -i input.10bit.x265.mkv -map 0:0 -c:v:0 hevc_vaapi -vf "scale_vaapi=w=-1:h=1080" -b:v 4027047 -map 0:1 -c:a:0 aac -b:a 384000 -ac 6 -map 0:s -scodec copy -map_metadata:g -1 -metadata JBDONEVERSION=1 -metadata JBDONEDATE=2020-06-06T20:52:36.072Z -map_chapters 0 output.8bit.x265.mkv

  



  The error I get is :

  



  [hevc_vaapi @ 0x5568b27fb1c0] No usable encoding entrypoint found for profile VAProfileHEVCMain10 (18).

Error initializing output stream 0:0 -- Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height


  



  From what I can tell ffmpeg looks at the source and selectes VAProfileHEVCMain10 instead of VAProfileHEVCMain. I'd like to force it to output 8-bit.

  



  I've tried adding -pix_fmt yuv420p but that gives me this error :

  



  Incompatible pixel format 'yuv420p' for codec 'hevc_vaapi', auto-selecting format 'vaapi_vld' 


  



  I've also tried making this change to the command : "scale_vaapi=w=-1:h=1080,format=yuv420p"

  



  However that gives me the error :

  



  Impossible to convert between the formats supported by the filter 'Parsed_scale_vaapi_0' and the filter 'auto_scaler_0'

Error reinitializing filters!


  



  Any suggestions ?

  


• avformat/mxfdec : Read Mastering Display Colour Volume from MXF

  9 septembre 2020, par Harry Mallon

  avformat/mxfdec : Read Mastering Display Colour Volume from MXF
  Described in Annex B SMPTE ST 2067-21:2020
  Signed-off-by : Harry Mallon <harry.mallon@codex.online>
  

  • [DH] libavformat/mxf.c
  • [DH] libavformat/mxf.h
  • [DH] libavformat/mxfdec.c
  • [DH] libavformat/mxfenc.c

• How to increase the compression ratio of a JPEG2000 file with "avenc_jpeg2000" GStreamer encoder ?

  10 juillet 2023, par qfr.bertin.group

  I'm using the plugin avenc_jpeg2000, from gst-libav module, combined with videotestsrc and filesink plugins for encoding a raw picture to a JPEG2000 picture :

  


  gst-launch-1.0 videotestsrc num-buffers=1 ! avenc_jpeg2000 ! filesink location=/tmp/picture-ref.jp2


  


  This pipeline works and produce a 31.85 KiB (32,616) file.

  


  Pipeline graph

  


  Now, I want to divide the size of my output file by two by increasing the compression ratio of the encoder avenc_jpeg2000. To achieve this, I want to minimize the number of bits required to represent the image with an allowable level of distortion. I know JPEG2000 standard support lossless and lossy compression mode. For my use case, the lossy compression mode is acceptable.

  


  How should I proceed to increase the compression of my output file ? What encoder's properties should I play with for doing that ?

  


  My test configuration :

  


  


  • i.MX 8M Plus

    


  


  • GStreamer 1.18.0

    


  


  • libav 1.18.0 (Release date : 2020-09-08)

    


  


  


  I tried to play with "bitrate" and "bitrate-tolerance" properties, but it seems to have no effect on the size of the output file :

  


  gst-launch-1.0 videotestsrc num-buffers=1 ! avenc_jpeg2000 bitrate=100000 bitrate-tolerance=10000 ! filesink location=/tmp/picture-test-01.jp2


  


  I compare files by doing a checksum with sha224sum command :

  


  d0da9118a9c93a0420d6d62f104e0d99fe6e50cda5e87a46cef126f9  /tmp/picture-ref.jp2

d0da9118a9c93a0420d6d62f104e0d99fe6e50cda5e87a46cef126f9  /tmp/picture-test-01.jp2