Несоответствие скорости аудио и видеодорожек

In an MPEG-4 container, video and audio are synchronized using timestamps. Each video frame and audio sample is assigned a timestamp that indicates when it should be played back. When the container is played back, the video and audio decoders use these timestamps to ensure that the frames and samples are played back in the correct order and at the correct times.

When you split the video and audio streams and then connect them together, desynchronization can occur if the timestamps are not properly maintained. If the video and audio streams have different frame rates or if they are not aligned properly, this can cause the audio to become out of sync with the video.

To avoid this, it's important to make sure that the timestamps are properly maintained when splitting and recombining the video and audio streams. One way to do this is to use a program like FFmpeg, which can handle the synchronization of video and audio streams automatically.

When using FFmpeg to split and recombine video and audio streams, you can use the -copyts option to copy the timestamps from the input files to the output files. This ensures that the timestamps are maintained and the video and audio remain in sync.

$ ffmpeg -framerate 30 -i %04d.png -i original.mp4 -map 0:v -map 1:a -c:v libx264 -pix_fmt yuv420p -crf 18 -c:a copy  output_5.mp4