Recherche avancée

Sur d’autres sites (6695)

• libavformat : add RCWT closed caption muxex

  14 janvier 2024, par Marth64

  libavformat : add RCWT closed caption muxex
  Signed-off-by : Marth64 <marth64@proxyid.net>
  Raw Captions With Time (RCWT) is a format native to ccextractor, a commonly
  
  used open source tool for processing 608/708 closed caption (CC) sources.
  
  It can be used to archive the original, raw CC bitstream and to produce
  
  a source file file for later CC processing or conversion. As a result,
  
  it also allows for interopability with ccextractor for processing CC data
  
  extracted via ffmpeg. The format is simple to parse and can be used
  
  to retain all lines and variants of CC.
  A free specification of RCWT can be found here :
  
  https://github.com/CCExtractor/ccextractor/blob/master/docs/BINARY_FILE_FORMAT.TXT
  
  This muxer implements the specification as of 01/05/2024, which has
  
  been stable and unchanged for 10 years as of this writing.
  This muxer will have some nuances from the way that ccextractor muxes RCWT.
  
  No compatibility issues when processing the output with ccextractor
  
  have been observed as a result of this so far, but mileage may vary
  
  and outputs will not be a bit-exact match.
  Specifically, the differences are :
  
  (1)  This muxer will identify as "FF" as the writing program identifier, so
  
  as to be honest about the output's origin.
  (2)  ffmpeg's MPEG-1/2, H264, HEVC, etc. decoders extract closed captioning
  
  data differently than ccextractor from embedded SEI/user data.
  
  For example, DVD captioning bytes will be translated to ATSC A53 format.
  
  This allows ffmpeg to handle 608/708 in a consistant way downstream.
  
  This is a lossless conversion and the meaningful data is retained.
  (3)  This muxer will not alter the extracted data except to remove invalid
  
  packets in between valid CC blocks. On the other hand, ccextractor
  
  will by default remove mid-stream padding, and add padding at the end
  
  of the stream (in order to convey the end time of the source video).
  

  • [DH] Changelog
  • [DH] doc/muxers.texi
  • [DH] libavformat/Makefile
  • [DH] libavformat/allformats.c
  • [DH] libavformat/rcwtenc.c
  • [DH] tests/fate/subtitles.mak

• avcodec/mdec : DC reading for STRv1 is like STRv2

  2 janvier 2024, par aybe aybe

  avcodec/mdec : DC reading for STRv1 is like STRv2
  As I understand, support for .STR files is broken for almost 10 years now (since 161442ff2c4b0dd8a5072c6bbe6bf55303fffccf it seems).
  Currently, ffmpeg fails with tons of errors like this on version 1 STRs, e.g. Wipeout 1 :
  
  [mdec @ 00000000027c72c0] ac-tex damaged at 1 9
  What happens is that only the audio is present in the video file.
  Anyway, that one character patch fixes the problem, video is now rendered.
  Signed-off-by : aybe <aybe@users.noreply.github.com>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/mdec.c

• Issue with yt-dlp and FFMPEG Converting Webm to MP4 for 360 video : Unsupported channel layout "ambisonic 1"

  22 janvier 2024, par William L W L

  I am trying to convert .webm files to mp4. These are 360 videos that have been downloaded using yt-dlp.

  


  I have been using this command successfully, but it does not work on an M2 macbook pro. It works fine on PC.

  


  ffmpeg -y -i "/Users/x/Movies/Tropical_Rainforest_360.webm" -c:v libx265 -preset fast -crf 21 -vf "scale=4096x4096:out_range=full" -pix_fmt yuvj420p -aspect 1:1 -movflags faststart "/Users/x/Movies/Tropical_Rainforest_360.mp4"


  


  The error messages are as follows :

  


  [aac @ 0x12ae1fea0] Unsupported channel layout "ambisonic 1"
[aac @ 0x12ae1fea0] Qavg: nan
[aost#0:1/aac @ 0x12ae1fc30] Error while opening encoder - maybe incorrect parameters such as bit_rate, rate, width or height.
Error while filtering: Invalid argument
[swscaler @ 0x110dd0000] deprecated pixel format used, make sure you did set range correctly
[swscaler @ 0x120158000] deprecated pixel format used, make sure you did set range correctly
[swscaler @ 0x130208000] deprecated pixel format used, make sure you did set range correctly
    Last message repeated 1 times
[out#0/mp4 @ 0x600003f8c480] Nothing was written into output file, because at least one of its streams received no packets.
frame=    0 fps=0.0 q=0.0 Lsize=       0kB time=N/A bitrate=N/A speed=N/A    
Conversion failed!



  


  Context : I work in an educational setting which caters for vulnearble pupils. We cannot use Youtube in real time, this is mainly due to adverts or suggested videos that may trigger our pupils. Some children have mental health issues. Some children have also not been outdoors for several months/years due to medical conditions. We use 360 videos and VR to help bring the outside world inside, The YoutubeVR app is not an option since there is no way to install adblockers.

  


  The same script above works fine on a PC virtual machine which I can remote into from my Mac.