audio video sync

[chazz spacey]

when i extract .h264(as mp4) and .ac3 files from mkv and then import them to adobe premiere the audio is 5-6 frames shorter than video. how to find audio delay without "lips move"? any tool? i already post thread about that but didn't get what i need. so question is: what tool can find audio delay?

[ndjamena]

If your original mkv doesn't have tags in it, remux it with MKVMerge to get the tag with total duration, then open the file with MKVInfo GUI, show all the elements and find the timecodes of the first frames for each track in the clusters, that will tell you the delay. That should give you everything you could possibly need, or would you prefer a simpler way?

[chazz spacey]

If your original mkv doesn't have tags in it, remux it with MKVMerge to get the tag with total duration, then open the file with MKVInfo GUI, show all the elements and find the timecodes of the first frames for each track in the clusters, that will tell you the delay. That should give you everything you could possibly need, or would you prefer a simpler way?

what the hell is that all?!
what are these words, numbers mean?
is delay 256 ms?

[ndjamena]

There's no delay in there, the 256ms time stamp is for the second block of frames for each audio track. If the audio is out of sync after being processed with Adobe, the problem doesn't originate with the MKV container.

If the audio ISN'T out of sync and is just a few frames shorter than the video then that's not really a problem, but if you like all you have to do is figure out a way to replace the gap with silence. Look at the file with MediaInfo and find the "duration" tags for each track (assuming they're there) if the audio is a few frames shorter it should show, if it doesn't then the problem lies solely with the Adobe software.

[chazz spacey]

There's no delay in there, the 256ms time stamp is for the second block of frames for each audio track. If the audio is out of sync after being processed with Adobe, the problem doesn't originate with the MKV container.

If the audio ISN'T out of sync and is just a few frames shorter than the video then that's not really a problem, but if you like all you have to do is figure out a way to replace the gap with silence. Look at the file with MediaInfo and find the "duration" tags for each track (assuming they're there) if the audio is a few frames shorter it should show, if it doesn't then the problem lies solely with the Adobe software.

mediainfo shows only with minutes.
can you please download this torrent(http://rutor.org/torrent/324405/beguwij-po-lezviju_blade-runner-1982-bdrip-720p-ot-leo...alnaja-versija) then extract video and first auido track and then tell if they are same or different length?
because in virtualdub, avidemux, sony vegas, adobe premiere shows different video lengths.
LeeAudBi v0.2b and adobe premiere shows same audio length. ok no problem. it is 1 h. 57 m. 36.864 s long.
but cant get video length right. i muxed .h264 file to mp4(with mkvtoolnix) and used different software to know length but each shows different length.
so important question is : lets say that i have a video that audio is 2 minutes shorter than video. and it's timing is: 1 minute silence(empty space) at the beginning and 1 minute silence at the end. and i extract video and audio and mux them again. question: Will it be like original video or this 2 minutes silence will be at the end? i think that is why there is a delay option in mkvtoolnix. how to know delay?
and there is "timecode file" option. how can i get timecode file?

[hech54]

can you please download this torrent(http://rutor.org/torrent/<b>XXXXXX</b>/beguwij-po-lezviju_blade-runner-1982-bdrip-720p...alnaja-versija) then extract video and first auido track and then tell if they are same or different length?

Are you a complete idiot?
Buy the damn disc and stop playing with torrent crap.
http://www.amazon.co.uk/Blade-Runner-Final-Blu-ray-Region/dp/B000VS20M2

[ndjamena]

can you please download this torrent(http://rutor.org/torrent/<b>XXXXXX</b>/beguwij-po-lezviju_blade-runner-1982-bdrip-720p...alnaja-versija) then extract video and first auido track and then tell if they are same or different length?

Are you a complete idiot?
Buy the damn disc and stop playing with torrent crap.
http://www.amazon.co.uk/Blade-Runner-Final-Blu-ray-Region/dp/B000VS20M2

THIS ^^^

But for what it's worth, there's not even the slightest hint of a delay in that file and each and every audio track is actually LONGER than the video track. The frame rate of the video is exactly 24/1.001 both in the container and in the stream itself.

Either you've got something wrong, or your adobe program has.

[chazz spacey]

can you please download this torrent(http://rutor.org/torrent/<b>XXXXXX</b>/beguwij-po-lezviju_blade-runner-1982-bdrip-720p...alnaja-versija) then extract video and first auido track and then tell if they are same or different length?

Are you a complete idiot?
Buy the damn disc and stop playing with torrent crap.
http://www.amazon.co.uk/Blade-Runner-Final-Blu-ray-Region/dp/B000VS20M2

i don't need that movie for watching. i need to cut scene from this. and i am just curious of are video and audio lengths same or not in this torrent. and you will help me a lot if you answer to this questions i lost a lot of time googling them.

[chazz spacey]

can you please download this torrent(http://rutor.org/torrent/<b>XXXXXX</b>/beguwij-po-lezviju_blade-runner-1982-bdrip-720p...alnaja-versija) then extract video and first auido track and then tell if they are same or different length?

Are you a complete idiot?
Buy the damn disc and stop playing with torrent crap.
http://www.amazon.co.uk/Blade-Runner-Final-Blu-ray-Region/dp/B000VS20M2

THIS ^^^

But for what it's worth, there's not even the slightest hint of a delay in that file and each and every audio track is actually LONGER than the video track. The frame rate of the video is exactly 24/1.001 both in the container and in the stream itself.

Either you've got something wrong, or your adobe program has.

what program do you use to get length information? mediainfo not showing in milliseconds.

[ndjamena]

MediaInfo doesn't know how long tracks in MKVs are at all, it just uses the file duration for all of the tracks. It's daft and since it doesn't actually know the bitrate either, if a single constant bitrate track is significantly shorter than the rest MediaInfo bitrates are completely useless too. You need to remux the file with MKVMerge, then, since MediaInfo doesn't seem to attach tags to the right tracks half the time, you need to either extract the tags into a text file with MKVExtract, or look at them with MKVInfo GUI or FFProbe.

[manono]

i need to cut scene from this. and i am just curious of are video and audio lengths same or not in this torrent

It doesn't make a bit of difference whether they're the same length or not, as long as they're in-synch. Haven't you already cut the scenes and tested yourself, rather than going on and on about this for days?

[chazz spacey]

uuuum.... i just found that mediainfo shows everything that i need. you need just do "Debug > Advanced Mode". it shows duration in milliseconds and shows delay too

[chazz spacey]

and it seems video delay is possible too. becouse mediainfo shows that video delay:0 ms. in mkvtoolnix delay option is not working. it fails.

[chazz spacey]

i downloaded mkvtoolnixv7.3.0 and delay worked.

[ndjamena]

Mediainfo doesn't know what the duration is even in advanced mode, try cutting a stream in half, remuxing the file again and checking what Mediainfo thinks the stream duration is. It's interesting that Mediainfo will alter the duration to be a multiple of the frame rate but it's still a waste of time.

And the current way MediaInfo determines delays is flawed, it just finds the timecode of the first video frame and decides that must be the delay, but modern video streams feature out of order decoding so the first video frame doesn't necessarily have to be to earliest. That will be fixed in the next version of MediaInfo, but for now, MKVInfo is the only way to find an accurate delay in an MKV.

[chazz spacey]

i dont understand what mkvinfo shows. it paralyzes my brain. what are these:
1

2

3

4

can you make a guide what is what, where i have to click to see duration, delay?
cant find these on documentation

[ndjamena]

A "Segment" is a file, Segment Size is the size of the file in bytes, your file is a little over 4gb.

At, is the position in the file the piece of data resides, you're looking at the innards of the actual file, it's components unsorted, unfiltered and in the order they exist in the file.

The size is how many bytes in the file that particular piece of information occupies.

Seek heads list the positions within the file of all the important information so programs don't have to read through the entire file to find anything.

An ebmlvoid is empty space that anything reading the header should ignore, if adding information to the header a header editor can fill the ebmlvoids instead of adding the information to the end of the file.

Codec Private Data is data decoders need to properly decode Tracks, Codec Private Length is the size of the Codec Private Data.

Timecode scale is how the file measures time, in the case of your file it measures time at ratio of one to one million nanoseconds.

Timecodes are when things start.

A UID is how Tags, Chapters and other file commands identify each segment and each component within a segment.

Track Type is the... type of the track - video, audio, subtitle.

A Block is a group of Frames for a particular track and a Cluster is a group of Blocks.

It's all here:
http://matroska.org/technical/specs/index.html

Just be happy you're looking at the bits that actually make sense.

[chazz spacey]

oh, i was looking at mkvtoolnix documentation.
i don't understand >90% of this. and it becomes harder to understand when english is bad. right now i need: where to look in mkvinfo to know is there delay or not.
so where to look in mkvinfo? just give a short answer please)
and i can see duration only in "segment information". i think it is audio track duration. but when you look at segment tracks there are no tracks' durations.
for test i set the delay to 20 sec in mkvtoolnix and checked it in mediainfo and it shows delay 20 sec. and in 'general' section it shows same duration which mkvinfo shows in 'segment information'. doesn't it mean that mediainfo works right?
and i need avi info tool too that can show delay information]
i found YAAI and it shows audio delay. it would be better to see your opinion on this.
don't forget:

right now i need: where to look in mkv info to know is there delay or not.
so where to look in mkvinfo? just give a short answer please)

[ndjamena]

The first screen shot you gave gives the delay, just look at the SimpleBlocks (or Blocks) and find the first timecode for the track number you're interested in.

MediaInfo only looks for the first frame in a stream, for the most part that will give the correct answer, but when a stream uses out of order decoding MediaInfo will give out the wrong answer. It took me a long while to figure that out and post the bug on the MediaInfo Forum, Jerome has recognised the problem and it will be fix in the next update. Generally, if MediaInfo reports a delay of 0 in the video stream it will be correct, anything more than that and what it returns is questionable. I'm waiting patiently for the next version of MediaInfo so I can stop telling people that. Unless Jerome updates mediainfo to recognise the new statistic tags, the program still won't know how long each stream is. To find that you'd need to remux the file with MKVMerge (because currently that's the only program that adds the tags) and a tag called "duration" should be added to the end of the file, if you look at the file with mediainfo and cross your fingers, mediainfo MIGHT attach the tags to the correct tracks, otherwise you'd need to look at the file in MKVInfo, the tags section should be somewhere near the end of the file, then you need to match the UIDs in the tags to the trackUIDs. Or if you like you could download FFProbe and point your file at it, it should attach the tags to the proper tracks.

I was hoping MediaInfos Delay problem and MKVTag reading would be fixed by now, but Jerome has more important things to do.

[chazz spacey]

in LeeAudbi and adobe premiere audio track duration is same but in ffprobe it is different.
extracted this audio file with mkvextract



and i find trackuid in tags. but i don't know what to do next with this . can you explain again how to see track duration in mkvinfo?

[Cornucopia]

ffprobe is wrong.
If the total # of bytes is 4386000 and the audio file is 48kHz/16bit/2ch (aka 1536000bps), ffprobe's "BPS" designator is wrong. Also the duration calculation based on it is wrong. 4386000 * 8 = 35088000bits. Divide that by the true bps (1536000) and you have 22.84375: exactly what LeeAudibe told you. If you divide the total by the ffprobe-stated bitrate (1538137 bps), you get your ffprobe-derived "22.812..." duration.

I'm guessing it is a mis-judged assumption of bitwise prefix nomenclature or something.

Scott

BTW, Premiere matches LeeAudibe, it's just rounding down to lesser # of decimal places.

[ndjamena]

Except it's not FFProbe saying that, FFprobe is just repeating what is in the tags, tags which were written in by MKVMerge. It's possible, (though unlikely) the audio has been stretched in some way, but Mosu should probably look into this anyhow.

[ndjamena]

Ticket:

https://trac.bunkus.org/ticket/1075

I guess that's another version I'm waiting for.

[chazz spacey]

what does it mean in a simple way?

Oh, I see, it's setting duration to the time code of the last frame, without taking into account the duration of the frame itself.

and the reason why i want to know the duration of the track(more important video track duration) that i want to be sure when i mux it into mp4 the duration will not change. and when i muxed .h264 to mp4 with yamb start time changed from 0 to 0.083417. ffprobe told me. so i am completely lost. all i want to know video track duration and then check if i muxed it right. if the duration is same after mux then i muxed it right.

and i find trackuid in tags. but i don't know what to do next with this . can you explain again how to see track duration in mkvinfo?

[poisondeathray]

Just to revisit the original issue - Chances are your original problems with sync are from trying to edit elementary video (or did you mean MP4 wrapped with separate audio?). Premiere works better when video & audio is in a container if you deal with compressed audio. Obviously it can't open MKV, but did you try importing it mutiplexed as MP4 or a transport stream (TS, M2TS ) ? ie. just rewrap the original MKV

The problem with compressed audio is there is always be some sort of delay. It varies by sample rate, by audio type. Only uncompressed audio will be perfectly aligned with no delay, otherwise the container will have muxing +/- delay to compensate. When you demux you lose that relationship. By importing multiplexed A+V, premiere keeps that relationship

[chazz spacey]

Just to revisit the original issue - Chances are your original problems with sync are from trying to edit elementary video (or did you mean MP4 wrapped with separate audio?). Premiere works better when video & audio is in a container if you deal with compressed audio. Obviously it can't open MKV, but did you try importing it mutiplexed as MP4 or a transport stream (TS, M2TS ) ? ie. just rewrap the original MKV

The problem with compressed audio is there is always be some sort of delay. It varies by sample rate, by audio type. Only uncompressed audio will be perfectly aligned with no delay, otherwise the container will have muxing +/- delay to compensate. When you demux you lose that relationship. By importing multiplexed A+V, premiere keeps that relationship

i just need to know that video muxed right. i dont need audio in mp4 container. because i can import extracted ac3 into adobe premiere but cant import .h264 and there is no delay in original mkv file. so after extracting audio and video i import them to adobe then i set start to 0.000 sec of each file. so no sync problem then.

[poisondeathray]

So there is no problem? I thought you had a 5 frame sync issue?

Watch and listen to the the audio, that's how you know it muxed right.

[manono]

Watch and listen to the the audio, that's how you know it muxed right.

I've thought from the beginning this whole thread was a waste of space and time. If, after you're done, it's in synch, then there was no problem to begin with.

If it winds up out of synch (which doesn't seem to be the case here) then put it back in synch by finding and removing the delay.

[poisondeathray]

Ultimately, testing sync with your ears and eyes is the standard

All the other things you're doing to test or find information can be problematic. Duration of video vs. audio isn't necessarily good indicator because audio can have silent samples, and compressed audio usually has some padding. +/- muxing delay isn't necessarily a good indicator because different programs calculate it slightly differently

[chazz spacey]

ok.
btw, i didn't get how to look to track duration with mkvinfo.
ndjamena, will you explain it to me again?