trying to convert stuttering video but having problems

[billsantos]

Recently I downloaded four streaming videos. Three of them play at 24 fps and present no problems. The fourth however plays at something around 23.5 or 23.976 fps and shows significant stuttering. At first I used a program called AVIdemux to change frame rate from 23.5 to 24 fps. This solved the stuttering, but now I am left with out of sync audio that I can't seem to remedy. AVIdemux seems to allow audio frame rate changes from NTSC to PAL or similar, but I can't input a deluxe change. I've tried adjusting the audio offset, but the longer the video plays, the more out of sync the audio becomes. Need some help here..... if I change the video from 23.5 to 24 fps, what has to be done exactly to the audio to compensate? Is there software that can perform both tasks simultaneously and successfully?

Thanks.

I don't really know how to solve this with AviDemux, but you can try the following:
Repairing FLV files by remuxing them with freeware FLV Extract and mp4box

[billsantos]

I tried this method, but it didn't work. The FLVextract program did not extract the needed files and I am trying to do this without having to convert, since conversions cause loss of quality each time.

The method I'm using involves extracting and resampling the audio file separately from the video and then merging the two once the audio file is in sync. However, I have not found an easy way to do this and the task is quite tedious. It isn't as simple as resampling the audio as sometimes an audio shift also appears to be needed. Due to all the time it's taken me to realign just one or two movies, I question whether future movies are worth it. I thought surely someone might have a more efficient method, or could recommend some software that would aid the task but so far there has been limited response.

I have been running into this problem with standard HD and full HD videos from CBS. Full HD are already at 24 fps film speed and should present no problems when I view them on the large screen LCD tv. However, the standard HD vids have been another matter. They seem to play at 23.5 to 23.976, show significant stuttering, and they aren't going to display properly on most LCD's because they are not at 24 fps. Just trying to change that small amount of frame speed (from 23.5 to 24 fps) and keep the audio in sync has been one of the most difficult tasks I've ever dealt with in audiovisual. I had hoped someone else had a reasonable solution. CBS is popular and I'm sure others have been running across the same issues with HD vids.

Have you tried to repair your files with GetFLV? You can use a demo version for repairing FLV files with it.

What program do you use for downloading from CBS?

[billsantos]

I've been using GetFLV. Yes, I did try to repair the standard HD vids, but to no avail. The only thing I've been able to do so far is as I've already described, which eliminates 90% of the stuttering but leaves the audio to a tedious fix! Luckily, not all of the vids I want are in HD, with most being Full HD, so I'm lucky and the Full HD's don't have any problems.

[blimey]

Originally Posted by billsantos

I tried this method, but it didn't work. The FLVextract program did not extract the needed files and I am trying to do this without having to convert, since conversions cause loss of quality each time.

Which file did FLVExtract fail to extract?

Both HD and HD-1080p files at CBS are h.264/aac. FLVExtract shouldn't have any problem with either. Using this method is not transcoding (converting), it is only demuxing and remuxing. There is no loss.

Originally Posted by billsantos

The method I'm using involves extracting and resampling the audio file separately from the video and then merging the two once the audio file is in sync. However, I have not found an easy way to do this and the task is quite tedious. It isn't as simple as resampling the audio as sometimes an audio shift also appears to be needed. Due to all the time it's taken me to realign just one or two movies, I question whether future movies are worth it. I thought surely someone might have a more efficient method, or could recommend some software that would aid the task but so far there has been limited response.

You shouldn't have to do any of this. Any "stuttering" or sync issues are most likely due to the flv container produced by GetFLV.

Originally Posted by billsantos

I have been running into this problem with standard HD and full HD videos from CBS. Full HD are already at 24 fps film speed and should present no problems when I view them on the large screen LCD tv. However, the standard HD vids have been another matter. They seem to play at 23.5 to 23.976, show significant stuttering, and they aren't going to display properly on most LCD's because they are not at 24 fps. Just trying to change that small amount of frame speed (from 23.5 to 24 fps) and keep the audio in sync has been one of the most difficult tasks I've ever dealt with in audiovisual. I had hoped someone else had a reasonable solution. CBS is popular and I'm sure others have been running across the same issues with HD vids.

23.976 is a standard framerate. This by itself does not cause the issues you describe.

I've seen issues with flv files produced by getflv, but they are always solved by simple demuxing and remuxing (which eliminates getflv's faulty .flv container).

Carefully follow the steps with FLVExtract and mp4box again, and describe exactly where you have trouble.

You can also quickly rebuild the container with ffmpeg like this:

ffmpeg -i "CBS_file.flv" -vcodec copy -acodec copy "NewName.flv"

--or this:

ffmpeg -i "CBS_file.flv" -vcodec copy -acodec copy "NewName.mkv"

[billsantos]

Originally Posted by blimey

Which file did FLVExtract fail to extract?

When I tried Flvextract, it extracted to AVI and MP3, so I wasn't sure how to proceed from there. On the Flvextract page, it says nothing can be done if it didn't extract as the files you specified, so I wasn't sure how to proceed from there.

Originally Posted by blimey

Both HD and HD-1080p files at CBS are h.264/aac. FLVExtract shouldn't have any problem with either. Using this method is not transcoding (converting), it is only demuxing and remuxing. There is no loss.

I'm certainly willing to give it a second try if you could tell me what to do with the AVI/MP3 files. Practically anything is better than doing the process I came up with.

Originally Posted by blimey

You can also quickly rebuild the container with ffmpeg like this:

ffmpeg -i "CBS_file.flv" -vcodec copy -acodec copy "NewName.flv"

--or this:

ffmpeg -i "CBS_file.flv" -vcodec copy -acodec copy "NewName.mkv"

Is ffmpeg a separate program and would I still need Flvextract/ mp4box?

Thanks for any help.

[blimey]

Originally Posted by billsantos

When I tried Flvextract, it extracted to AVI and MP3, so I wasn't sure how to proceed from there. On the Flvextract page, it says nothing can be done if it didn't extract as the files you specified, so I wasn't sure how to proceed from there.

If flvextract is producing an .avi file for the video track, then the video is not h.264. It may be flv1 or vp6. Do you know what video codec is used? Do you have a link for the video?

You can get ffmpeg here.

[billsantos]

Originally Posted by blimey

If flvextract is producing an .avi file for the video track, then the video is not h.264. It may be flv1 or vp6. Do you know what video codec is used? Do you have a link for the video?

It's vp6. Here is a link to one of them:

http://www.cbs.com/hd/video.php?cid=&pid=th2_IRo1CqOp3GtVMF5_ch_YMAgzoU9M&play=true&offset=0&show=star_trek_remastered

If you look at the episodes below this one, anything I'm downloading with GetFLV that offers a maximum of HD and not 1080p is coming out stuttered (the 1080p ones play fine).