Audio and video not in sync after compression

[Simon Hustings]

Hey Nate,

How is the audio out of sync? Does it drift over time or is it out of sync from the beginning of the clip? Why do you want to reduce the file size before compression? Pro Res is pretty hefty compared to HDV so it would be a big file anyway!

All the best,

Simon

“Is it me or do I spend half my life watching little grey bars turn into little blue bars??”

[Nathan Lehner]

The audio starts at the right spot then drifts out of sync. . . its get out pretty quick. When I play the mpeg4 on my imac if I pause and restart in the middle, it will again start in sync but then right away it is out of sync again. In FCP everything looks and plays fine. When I burned a disk and played on a PC it would just pause and skip.

I have know real good reason for why I’m using prores422 other than I’m just experimenting with differnt formats to find the best work flow. I was thinking that maybe if my file size was not so big it might compress to an mpeg 4 better? I really don’t know! When I did the same thing with SD DV on a different project I had no problems.

Thanks for your help,
Nate

[John Fishback]

Did you Send to Compressor or export a QT and use that in Compressor? If you used the Send to Compressor workflow, try Export QT Using Current Settings. Then use that file in Compressor to make the mp4. Also, if you have any gaps between video clips in your sequence, fil the gaps with slug.

John

MacPro 8-core 2.8GHz 8 GB RAM OS 10.5.8 QT7.6.4 Kona 3 Dual Cinema 23 ATI Radeon HD 3870, 24″ TV-Logic Monitor, ATTO ExpressSAS R380 RAID Adapter, PDE enclosure with 8-drive 6TB RAID 5
FCS 3 (FCP 7.0.2, Motion 4.0.2, Comp 3.5.2, DVDSP 4.2.2, Color 1.5.2)

Pro Tools HD w SYNC IO & 192 Digital I/O, Yamaha DM1000, Millennia Media HV-3C, Neumann U87, Schoeps Mk41 mics, Genelec Monitors, PrimaLT ISDN

[Michael Sacci]

If your audio is in sync at the beginning or if you stop and restart anyplace within the file, it is the file that is the issue. FCP has done it’s thing.

There are many types of mp4 flavors, you need to give specific settings. I would use a H264 preset, it is the most widely used mp4 compression. Also try making it in compressor from an export QT as said above.

[Nathan Lehner]

Cool, I’ll give that a try. I just compressed to a DVD and that worked fine so I’ll try changing the mpeg4 seting in compressor.

nate

[Michael Sacci]

[Nathan Lehner] “I just compressed to a DVD”
As in a SD DVD or BluRay, if you are going to a SD DVD you never want to go to H264 or any other mpeg4, it uses m2v codec, you would want to use the ProRes file for DVD encoding. You need to give complete workflow objective and settings if you want to get clearer help.

[Simon Hustings]

Check your audio sample rates too. I’ve seen issues in the past when encoding to one of the mpeg 4 flavours. If the audio bit rate is too low, the audio can drift. Double check the framerate of the mpeg4 too. Mismatching frame rates and audio rates can cause issues.

All the best,

Simon

“Is it me or do I spend half my life watching little grey bars turn into little blue bars??”

[Nathan Lehner]

I filled in the gaps with a slugs, exported to QT directly from FCP using current setting. That looks fine. Then tried the mp4 template in compressor and its still not in sync. What appears to be happening is the video is playing slower (slightly jumpy) than the audio. Audio sounds fine. The frame rate in the mp4 template is at 29.9 which is how it was shot. I also tried the H.264 QT template and that looks great but that file is to big to go on a SD DVD. AAHH

Again, when I used the mpeg4 template with SD video it was fine. . . does this have something to do with the fact that I’m in HD 422 prores? Would changing my sequence setting help or would that not matter because the footage was captured in 422 prores? Also, you all have mentioned about the many mpeg4 “flavors” there is only one mpeg4 format in compressor?

Thanks so much for all your time and help,

Nate

[John Fishback]

Using ProRes won’t negatively affect anything. Something else is going on. I’m confused about whether you’re trying to make a DVD or a standalone mp4 file. If a DVD, do as Michael suggests above and encode a mpeg-2(mv2) file. Don’t use a mp4 in a DVD. If it’s just a mp4 file, grab an image of Compressor’s Inspector and post it here so we can see all the parameters of your encode. That might spark some ideas.

John

MacPro 8-core 2.8GHz 8 GB RAM OS 10.5.8 QT7.6.4 Kona 3 Dual Cinema 23 ATI Radeon HD 3870, 24″ TV-Logic Monitor, ATTO ExpressSAS R380 RAID Adapter, PDE enclosure with 8-drive 6TB RAID 5
FCS 3 (FCP 7.0.2, Motion 4.0.2, Comp 3.5.2, DVDSP 4.2.2, Color 1.5.2)

Pro Tools HD w SYNC IO & 192 Digital I/O, Yamaha DM1000, Millennia Media HV-3C, Neumann U87, Schoeps Mk41 mics, Genelec Monitors, PrimaLT ISDN

[Nathan Lehner]

I’m trying to make a stand alone mpeg4 file and save it to a disk (DVD-R). The problem is occuring though right after the QT file is compressed. I made an m2v file just to see if a standard dvd would work and it did. For some reason its just when I try to put it into an mpeg4 format.

I’m working remotely and my imac cant be connected to the web to copy the image of the inspector but here is where I am at:

File Format- mpeg4
extension- mpeg4
allow job segmenting- checked
Video enabled- checked
ISMA profile- basic
Frame Rate- 29.97
Keyframe interval- 15
Bit Rate- medium vbr

I have been experimenting with different combinations of Bit Rate and frame rate but that does not seem to be helping.

Thanks again,
Nate