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• Does using FFMPEG source code execute faster than using it by commands on Android ? [on hold]

  13 décembre 2018, par Valgrind1691

  I am using FFMPEG library for video processing on Android application. I use it by framing commands. However the processing time is too much even for short videos and using preset as ultrafast and all possible online suggestion for optimizing commands.
  I was wondering if writing C/C++ code using FFMPEG source to do all the process that command is doing and create a library for Android to be consumed using JNI will it make process faster ?

• FFMPEG - How to setup volume when merging two audio streams

  6 octobre 2014, par N3sh

  I just recently entered the magic and scary world of FFMPEG and, although I found quite a lot of guides online, I need help for my current problem.

  I am merging only audio files and I would like to be able to select their volume.

  Here is my current code for merging 2 files :

  ffmpeg -i test\audio00.mp3 -i test\audio01.mp3 -filter_complex amerge 
  
  -c:a libmp3lame -q:a 0 test\output_overlay.mp3

  I tried the following code, extracted from another answer here on SO (the User was also handling video), but it doesn’t work for me :

  ffmpeg -i test\audio00.mp3 -i test\audio01.mp3 -filter_complex "[0:a]volume=0.9[a1];  
  
  [1:a]volume=0.781250[a2]; [a1][a2]amerge,pan=stereo:c0code>

  I got this error :

  [AVFilterGraph @ 030fa8c0] The following filters could not choose their formats: 
  
  Parsed_amerge_2 Consider inserting the (a)format filter near their input or output.

  Is there a simple way to change the volume for the two streams (even for just the second one, it’s the background music) with FFMPEG ?

  P.S. Also, is it possible to have some sort of ’preview’ before actually rendering the file ?

• Adding retry connection logic to ffmpeg(rtmp)

  16 octobre 2014, par gaurav

  I am trying to create a video mosaic using ffmpeg. My full command looks like this -

  ffmpeg -i rtmp://localhost:1935/live/output1 -i rtmp://localhost:1935/live/output2 -i rtmp://localhost:1935/live/output3 -i rtmp://localhost:1935/live/output4 -filter_complex "nullsrc=size=640x480 [base]; [0:v] setpts=PTS-STARTPTS, scale=320x240 [upperleft]; [1:v] setpts=PTS-STARTPTS, scale=320x240 [upperright]; [2:v] setpts=PTS-STARTPTS, scale=320x240 [lowerleft]; [3:v] setpts=PTS-STARTPTS, scale=320x240 [lowerright]; [base][upperleft] overlay=shortest=0 [tmp1]; [tmp1][upperright] overlay=shortest=0:x=320 [tmp2]; [tmp2][lowerleft] overlay=shortest=0:y=240 [tmp3]; [tmp3][lowerright] overlay=shortest=0:x=320:y=240"  -filter_complex amix=inputs=4:duration=longest  -c:a aac -strict -2 -ar 44100  -c:v libx264 -f flv rtmp://localhost:1935/live/myStream

  This works well as long as all 4 input streams are running. But say one of the stream drops for sometime and comes back online. The output continues to show this stream as stuck (paused). Because once the stream drops (AVERROR_EOF) ffmpeg stops trying to get more packets from the input stream. I have to restart the ffmpeg process to get back everything to work again.

  Is there a way to add a retry logic here which will tell ffmpeg to keep trying to process all input sources as long as process is alive ?