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• Best way to go about video playback for WebAssembly, Linux, Windows, and Android

  13 janvier 2021, par Michael Macha

  I'm currently working on a game as a passtime during quarantine. It currently builds, via a Makefile, for WASM, Linux, and Windows ; and is eventually planned to be ported to Android through NDK. The API used is (primarily) SDL, with SDL Image and SDL Mixer, and all graphics go through OpenGL.

  


  As of the moment, all graphics, sound, and control is running perfectly ; but I would like to add video cut scenes and I'm uncertain of how to do this with WASM. I recognize that maybe half of the system resources are available in a browser, and am willing to drop fidelity in the web version to compensate. Currently, all code is in C and GLSL ; but if I need to I can add C++, or a little extra JavaScript.

  


  My compilers, for each platform, are gcc, emcc, and mingw32. They're all called through Maketools. As of the moment, it looks like I can just use FFMPEG for gcc & mingw ; but what's best for emcc, which does not have an FFMPEG port available ? Will I need to call something else, or use some specific browser function ? What is the simplest way to go about this, and does anyone have a basic tutorial for in-browser video with WebAssembly ?

  


  For a little further data, I'm debuting my project on Itch.io. For a launched-in-browser game, they require a zip file with an HTML file called index.html, and any support files, within it. (Total file size is effectively limited to 1 GB.) I'm expecting a minimum of 640x480 resolution, but would prefer higher. I'm currently digging through online examples but haven't yet found anything sufficiently basic. (This might change as I keep digging, and I'll update the question if I find anything.)

  


• lavu/tx : implement 32 bit fixed point FFT and MDCT

  9 février 2020, par Lynne

  lavu/tx : implement 32 bit fixed point FFT and MDCT
  Required minimal changes to the code so made sense to implement.
  
  FFT and MDCT tested, the output of both was properly rounded.
  
  Fun fact : the non-power-of-two fixed-point FFT and MDCT are the fastest ever
  
  non-power-of-two fixed-point FFT and MDCT written.
  
  This can replace the power of two integer MDCTs in aac and ac3 if the
  
  MIPS optimizations are ported across.
  
  Unfortunately the ac3 encoder uses a 16-bit fixed point forward transform,
  
  unlike the encoder which uses a 32bit inverse transform, so some modifications
  
  might be required there.
  The 3-point FFT is somewhat less accurate than it otherwise could be,
  
  having minor rounding errors with bigger transforms. However, this
  
  could be improved later, and the way its currently written is the way one
  
  would write assembly for it.
  
  Similar rounding errors can also be found throughout the power of two FFTs
  
  as well, though those are more difficult to correct.
  
  Despite this, the integer transforms are more than accurate enough.
  

  • [DH] doc/APIchanges
  • [DH] libavutil/Makefile
  • [DH] libavutil/tx.c
  • [DH] libavutil/tx.h
  • [DH] libavutil/tx_int32.c
  • [DH] libavutil/tx_priv.h
  • [DH] libavutil/tx_template.c
  • [DH] libavutil/version.h

• ffmpeg commands to concatenate different type and resolution videos into 1 video and can be played in android [duplicate]

  24 août 2021, par Aalap

  I want to concatinate 4 different videos of 4 different resolution and type into 1 video which can be played in android. I am using ffmpeg ported on android using https://github.com/guardianproject/android-ffmpeg

  



  So I have these 4 different types of videos
1)

  



  ./ffmpeg -i 1.mp4 
Video: h264 (High), yuv420p, 1920x1080, 16959 kb/s, 29.85 fps, 90k tbr, 90k tbn, 180k tbc
Audio: aac, 48000 Hz, stereo, s16, 106 kb/s


  



  2)

  



  ffmpeg -i 2.mp4
Video: h264 (Constrained Baseline), yuv420p, 640x480, 3102 kb/s, 29.99 fps, 90k tbr, 90k tbn, 180k tbc
Audio: aac, 48000 Hz, stereo, s16, 93 kb/s


  



  3)

  



  ffmpeg -i 3.3gp
Video: h263, yuv420p, 1408x1152 [PAR 12:11 DAR 4:3], 2920 kb/s, 15 fps, 15 tbr, 15360 tbn, 29.97 tbc
Audio: amrnb, 8000 Hz, 1 channels, flt, 12 kb/s


  



  4)

  



  ffmpeg -i 4.3gp
Video: h264 (High), yuv420p, 352x288 [PAR 12:11 DAR 4:3], 216 kb/s, 24 fps, 24 tbr, 24 tbn, 48 tbc


  



  Audio : aac, 44100 Hz, stereo, s16, 92 kb/s

  



  So I am converting them to mpegts using following commands

  



  ./ffmpeg -i 1.mp4 -c:v libx264 -vf scale=1920:1080 -r 60 -c:a aac -ar 48000 -b:a 160k -strict experimental -f mpegts 1.ts
./ffmpeg -i 2.mp4 -c:v libx264 -vf scale=1920:1080 -r 60 -c:a aac -ar 48000 -b:a 160k -strict experimental -f mpegts 2.ts
./ffmpeg -i 3.3gp -c:v libx264 -vf scale=1920:1080 -r 60 -c:a aac -ar 48000 -b:a 160k -strict experimental -f mpegts 3.ts
./ffmpeg -i 4.3gp -c:v libx264 -vf scale=1920:1080 -r 60 -c:a aac -ar 48000 -b:a 160k -strict experimental -f mpegts 4.ts


  



  then concatenating the .ts files into f.ts and then creating a final .mp4 file from it using

  



  cat 1.ts 2.ts 3.ts 4.ts > f.ts
./ffmpeg -i f.ts -c copy -bsf:a aac_adtstoasc output.mp4


  



  But my f.ts also doesnt seem to play correctly in VLC on linux, it plays first 2 mp4's video + audio and it plays last .3gp's audio only.(Same for output.mp4 too) Could you please help me in figuring out what am I missing ?

  



  Thanks in advance