Doom9's Forum - View Single Post - Audio and video out of sync after encoding

tebasuna51 · 9th May 2019, 01:53

Video Frame = 1 image
Video Frame Rate = Number of images to show in 1 second.
A video with Constant Frame Rate 23.976 show a frame 41708333 ns
When a video have a Variable Frame Rate there are a different time to show each image.
You can obtain the info in a txt file from a mkv with:

mkvextract "input.mkv" timestamps_v2 0:"Video_times.txt"

Audio Frame = A set of audio Samples encoded together, for instance for AAC 1024 Samples Per Frame (SPF).
Audio Sample Rate = the number of audio Samples to play in 1 second (here 48000)

Audio Frame Rate is not relevant for audio and not related at all with Video Frame Rate.
The equivalent for Video Frame Rate is the Audio Sample Rate.

The Audio Sample Rate can't be variable and any control by timestamps of the audio can produce audio clicks and must be avoided.

9th May 2019, 01:53	#16 \| Link
tebasuna51 Moderator Join Date: Feb 2005 Location: Spain Posts: 6,915	Video Frame = 1 image Video Frame Rate = Number of images to show in 1 second. A video with Constant Frame Rate 23.976 show a frame 41708333 ns When a video have a Variable Frame Rate there are a different time to show each image. You can obtain the info in a txt file from a mkv with: mkvextract "input.mkv" timestamps_v2 0:"Video_times.txt" Audio Frame = A set of audio Samples encoded together, for instance for AAC 1024 Samples Per Frame (SPF). Audio Sample Rate = the number of audio Samples to play in 1 second (here 48000) Audio Frame Rate is not relevant for audio and not related at all with Video Frame Rate. The equivalent for Video Frame Rate is the Audio Sample Rate. The Audio Sample Rate can't be variable and any control by timestamps of the audio can produce audio clicks and must be avoided. __________________ BeHappy, AviSynth audio transcoder.