They can be used to transcribe dialogues for easier understanding. Since I'm using MP3, what is the packet size? Ideally, I could specify a packetsize (in the audio-encoder?) that matches my block size (512) to keep things consistent and simple.There are many reasons why one needs to add SRT subtitles to MKV, some of its benefits are but not limited to: One frame, for audio this is one packet of the specific audio type." I'm not clear on what numbers to use in the timecodes file.Īccording to mkvmerge documentation "For video this is exactly The video was much more laborious to produce, so I'd rather loose some sound than some frames. Will it force the video to match the audio or vice versa? I'm much less concerned with the duration than the sync. Reference, if I use the scene changes as timecodes for the audio, Is this the best approach (beyond trying to figure out what went wrong in the first place)? As I'm using my video frames as a Since I know the exact timing of scene changes, I should be able to generate "external timecodes" (from the blocks above) for mkvmerge to perfectly sync the output! Subquestions: I cannot figure out the cause of this nonlinearly increasing audio delay I've double and triple checked my math. I can't just shift or scale the audio to fit the video because of this nonlinearity. The worst part is that the audio lag is nonlinear! By non-linear, I mean that if I plot the lag against the location of that lag in time, I don't get a line, but what you see in the image below). When I combine the audio and video back together (currently using ffmpeg to generate mp4(v) mp3(a) in an MKV container), the audio and video start off in sync but increasingly drifts until it ends up being ~35 seconds off. I use these blocks in my audio code to treat the samples associated with each scene as a group. SceneOnsetBlock = sceneOnsetFrame*blocksPerFrame 
I store the frame onset of sceneChanges in a file in terms of cumulative blocks: blocksPerFrame = (48000 / 512) / 23.976 the audio changes on video scene change), so sync is crucial. I use scene changes in the video in the audio process (i.e.
I'm working on a project where video and audio are algorithmic interpretations of an MKV source file where I use ffmpeg -ss and -t to extract a particular region of audio and video to separate files.
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