Quicktime to AVI sync issue

[peter tron]

HI,

I have a Quicktime file that plays fine with no sync problems, but when I try to convert it to the default MPEG4 AVI mencoder, it goes out of sync.
I have tried selecting different frame rates (Pal 25 etc) but to no avail.

Any ideas?

Cheers!

Baz.

[poisondeathray]

check mediainfo view=> text copy & paste the info back here

You can try other software like xmedia recode, or avidemux

[peter tron]

Thanks for replying.

I downloaded the GUI version of mediainfo.

I dragged the filke into the main window, then selected view=> text.

This is what it showed:

Transfer characteristics : BT.709-2, SMPTE 170M, SMPTE 274M, SMPTE 293M, SMPTE 296M
Matrix coefficients : BT.470-4 System B, BT.470-4 System G, BT.601-4, SMPTE 170M, SMPTE 293M

Audio
ID : 8
Format : PCM
Format settings, Endianness : Big
Format settings, Sign : Signed
Codec ID : twos
Duration : 2h 57mn
Bit rate mode : Constant
Bit rate : 1 536 Kbps
Channel(s) : 2 channels
Sampling rate : 48.0 KHz
Bit depth : 16 bits
Stream size : 1.90 GiB (69%)
Language : English
Encoded date : UTC 2012-01-03 18:46:59
Tagged date : UTC 2012-01-03 18:53:12

Text
ID : 7
Format : Apple text
Codec ID : text
Duration : 2h 57mn
Bit rate mode : Variable
Bit rate : 1 bps
Stream size : 699 Bytes (0%)
Language : English
Encoded date : UTC 2012-01-03 18:46:59
Tagged date : UTC 2012-01-03 18:53:12
Material_Duration : 7454415
Material_StreamSize : 699

Have I done what you asked me correctly?

BR.

Baz.

[poisondeathray]

Nope, it seems to be missing the video information; it only lists the audio and text stream

Sometimes MOV can contain variable frame rate (VFR) video; AVI container doesn't support VFR . It should say in the video portion of mediainfo if the frame rate is variable

[peter tron]

Ahh, that was my mistake. I missed the video section when I copied and pasted.

Here it is again, in full:

Format : MPEG-4
Format profile : QuickTime
Codec ID : qt
File size : 2.77 GiB
Duration : 3h 21mn
Overall bit rate mode : Variable
Overall bit rate : 1 968 Kbps
Encoded date : UTC 2012-01-03 18:49:21
Tagged date : UTC 2012-01-03 18:53:12

Video
ID : 1
Format : DIVX
Codec ID : DIVX
Duration : 3h 21mn
Bit rate : 617 Kbps
Width : 720 pixels
Height : 304 pixels
Display aspect ratio : 2.35:1
Frame rate mode : Constant
Frame rate : 25.000 fps
Bits/(Pixel*Frame) : 0.113
Stream size : 890 MiB (31%)
Language : English
Encoded date : UTC 2012-01-03 12:55:43
Tagged date : UTC 2012-01-03 18:53:12
Color primaries : BT.709-2, SMPTE 274M, SMPTE 296M
Transfer characteristics : BT.709-2, SMPTE 170M, SMPTE 274M, SMPTE 293M, SMPTE 296M
Matrix coefficients : BT.470-4 System B, BT.470-4 System G, BT.601-4, SMPTE 170M, SMPTE 293M

Audio
ID : 8
Format : PCM
Format settings, Endianness : Big
Format settings, Sign : Signed
Codec ID : twos
Duration : 2h 57mn
Bit rate mode : Constant
Bit rate : 1 536 Kbps
Channel(s) : 2 channels
Sampling rate : 48.0 KHz
Bit depth : 16 bits
Stream size : 1.90 GiB (69%)
Language : English
Encoded date : UTC 2012-01-03 18:46:59
Tagged date : UTC 2012-01-03 18:53:12

Text
ID : 7
Format : Apple text
Codec ID : text
Duration : 2h 57mn
Bit rate mode : Variable
Bit rate : 1 bps
Stream size : 699 Bytes (0%)
Language : English
Encoded date : UTC 2012-01-03 18:46:59
Tagged date : UTC 2012-01-03 18:53:12
Material_Duration : 7454415
Material_StreamSize : 699

I noticed that it says that the frame rate mode is constant, and the frame rate is 25 (Pal).

Hmm.

Something else that was strange that I noticed. When I play the file in quicktime, it's fine, but VLC, which normally plays just about everything, doesn't playback the audio. I've never noticed that before.

[manono]

After being reencoded at 25fps, is the audio out of synch by the same amount all the way through, or does it get worse (more out of synch) as the movie goes along?

[peter tron]

Hi Manono,

I'll have to get back to you after I have completely re-encoded the whole file, as before I was just testing the first five minutes.

Baz.

[poisondeathray]

Unless mediainfo is incorrect, it's already mpeg4asp (divx) , you can probably re-wrap it with ffmpeg into avi container a lot faster than re-encoding, with no quality loss

But you might have encode the audio to PCM WAV

ffmpeg -i input.mov -vcodec copy -acodec pcm_s16le output.avi

[peter tron]

Too late, i've already done it!

In answer to the previous question:

The audio doesn't get progressively worse as the file goes on.

I was hoping for a simple solution, but I have the feeling that I've bitten off more than I can chew when I thought about trying to solve this problem.

[manono]

To answer the question, for future reference either remux with the delay taken into account, or remove the delay entirely using DelayCut, before then remuxing.

To determine the amount of the delay I use MPC-HC and the +/- keys to adjust the delay on the fly so I can figure it out.

[peter tron]

My mistake, I should have mentioned I use a Mac, so delaycut is of no use.

Can you point me in the right direction with regards to "remuxing"?

I assume you mean using ffmpegx to do this? Under the 'tools' tab, I only see 'mux' and 'demux', no 'remuxing'.

I have never done this, so I will need some basic tutoring.

[manono]

I don't use Macs so I have no idea. Remuxing is the same as muxing. If ffmpegx allows for setting a delay when muxing, do it that way then. Since the source file plays fine and when converted it's out of synch, I'm guessing the source file already has a delay set.

Otherwise, since the audio is PCM, if you have the use of a WAV editor you can either add silence or remove audio from the beginning to get rid of the delay.

[Cornucopia]

I usually consider remuxing = demuxing + muxing again.

Notice that the audio in the source is BIG ENDIAN. That is NOT the way LPCM WAV files store their samples (they use LITTLE ENDIAN), so one will have to do a byte swap in order for it to play correctly (remember, this was created on a Mac). Without this being done (at least SOMEWHERE in the software), what you'll hear will be very annoying static.

One way to convert this would be to use QT Pro. Their export-to-wav feature automatically includes a byte swap to little endian. (Plus, it might help fix the sync issue).

Scott

[manono]

I usually consider remuxing = demuxing + muxing again.

Hehe, I was using it slightly differently. He had already muxed once. I was suggesting either setting a delay in the muxer or fixing the delay in a WAV editor, and then remuxing (muxing again). But maybe the Big Endian/Little Endian stuff is the fix.

[poisondeathray]

i was talking about using command line ffmpeg , open up a terminal in mac (you need a mac ffmpeg binary)
http://guides.macrumors.com/Terminal

I assumed you knew how because you mentioned using mencoder

the command line above will convert to little endian , that' s what the "le" is for in "-acodec pcm_s16le"

if your previous conversion works, but only problem is constant sync offset, it might be easier for you to shift the audio . You can do that with avidemux

[peter tron]

OK, all I know is that I now split the audio & video into two seperate files.

I assume I have to mux these two together in ffmpegx.

But there is no sync offset control when you use the mux option in ffmpegx. Also, there is no option to preview what you are encoding to see if you need to change the sync.

[poisondeathray]

avidemux has a preview (assuming you want to fix what you have now , after the fact)

video=>copy
audio=> copy
format=> avi

under the shift box, under audio, enter the +/- ms shift value


you could probably use mpegstreamclip to encode to xvid, but again, IMO all these are suboptimal because you are re-encoding the video (losing quality and wasting time - it's much faster to re-wrap if you were starting from scratch)

[peter tron]

What shall I do?

Are you saying "re-wrapping" the quicktime file using the ffmpeg application is going to fix the sync issue?

I realize the above application is command-line based. I have never used the terminal on my Mac before, so I will probably need some help.

I should point out that I was using an audio editor on my Mac to edit and save the original AVI file as a quicktime file.
Saving as a quicktime file on this editor was the only option, as there was no AVI choice.
Also, there was an option to apply compression to the file, aswell as saving it as a quicktime file. I left it default (none).
There were other options in the list, such as 'Apple Lossless', 'Big Endian' etc.

[poisondeathray]

No, I'm saying it's probably easier just to fix what you have with avidemux , because it's only a constant sync issue (ie. just shift the audio relative to video)

And why would you even want AVI on a mac in the first place ?

[peter tron]

Right, i'll give avidemux a try, and i'll let you know how I got on.

Why AVI?

because it's everywhere, like mp3.

Most video files I come across are in this format, it works on just about every media player out there, it does what it says on the tin, as they say.

AVI also works in the majority of standalone DVD players, unlike MKV.

I'm assuming, file-wise, that you feel there are better formats to use for watching video filers on a computer?

it's a no-frills format that does the job, really. And that's good for me.

[poisondeathray]

yes that's a good reason, for standalone compatibility

mov is more compatible with macs, but can cause problems with pc's (MOV is an Apple format) . AVI is more compatible with PC's but can cause problems with macs (AVI is a microsoft video for windows format)