What is packet bitstream and what is it good for?

[chupacabra]

Hi dear forum members

most of the video files that are online are DivX/XviD packet bitstreamed files. My questions are:

- What is packet bitstreaming and how do you apply it? (I can't find anything on this using google)
- What is it good for and why do people encode with packet bitstreaming if rarely supported by DVD players?
- By the way I also want to ask what B-Frames are and what they are used for.

I've read a guide that showed how to remove packet bitstreaming using MPEG4-Modifier. The output file was
smaller and did not stutter on my DVD Player (Philips DVP 5960/12). So why use packet bitsreaming?

I uploaded a new firmware onto my DVD player and than the packet bistreamed testfiles from http://www.phunkyfish.com/ were playing correctly but some files are still stuttering. Maybe you can also help me with this problem. It is an DivX 5.1.1 with packet bitstream and a resolution of 640x480. Is this resolution too high for my DVD player? I removed packet bitstream and the video file is still stuttering. I have no clue. I tried several firmwares and the videos keep stuttering. 640x480 isn't that high of a resolution, is it?

Thanks for your replies in advance![/url]

[Baldrick]

640x480 should work but it could be something else like qpel, gmc. Can you identify the divx with gspot and post the details/screenshot here?

[chupacabra]

Hi thanks for replying so fast.

GSpot 2.70a export file content:

GSpot v2.70a avi file details:
------------------------------
Filename......: Dark Skies - 10 - We shall overcome.avi
Filesize.....: 400,642,022 bytes
Runtime......: 46:55.080 (70377 frames)
Video Codec..: DivX 5.1.1 (Maupiti) (B-VOP//)
Video Bitrate: 1000 kbps
Aspect Ratio.: 640x480 (1.333)
Framerate....: 25.000 fps
Audio Codec..: 0x0055 MPEG-1 Layer 3
Audio Bitrate: 128kbps 2ch CBR 44100Hz
Language.....: English

Screenshot:

[KBeee]

Try Googling for "packed bitstream" instead of packet bitstream and you'll get more results

[chupacabra]

Oooopsss... My fault. Thanks very much! Maybe someone can alter the title of the thread.

This is what I found I hope it helps other people who read this thread:

http://itsjustonesandzeros.blogspot.com/2007/01/what-is-packed-bitstream.html

Do you have any idea why the video file is stuttering on my DVD player?

[guns1inger]

Some players simply don't like packed bitstream encoding, some don't care.

[chupacabra]

Some players simply don't like packed bitstream encoding, some don't care.

Ok but I wrote that I unpacked the AVI and it is still stuttering. That is why I posted the screenshot.

[guns1inger]

What is your native format ? The file in question is a PAL file. Without being able to see what constitutes 'stuttering' on your system, it could be format conversion at the player level (PAL -> NTSC). If you are in a PAL region then it probably isn't.

Otherwise there is nothing special or odd about your video that would make it play badly.

[chupacabra]

I'm in Hungary. Hungary is using PAL as the television system standard. So no idea why it is stuttering?

[lingyi]

Try running it through Divfix as described in my post here:

https://forum.videohelp.com/topic333766.html

It sounds like it may be the same problem.

[chupacabra]

I did and it reported no error. Than I clicked "Rebuild Index" and it created a file that is as big as the original one accurate to a byte.

I than watched the video on my PC and I saw that it is already stuttering on it. I re-encoded it with DivX 5.2.1 and the video is still stuttering. Do you have any idea how I can fix this?

[guns1inger]

Does the original stutter when you play it on your PC ?

[chupacabra]

Yes it does. That's what I wanted to say.

[guns1inger]

Then this probably has little to do with the player, and more to do with the file itself.

Can you give a clearer description of the stuttering ? Does the file stop, or does the image judder ? Does it happen all the time, or only during pans and zooms ?

Does it happen in all players ? Some players use external codecs, some use their own.

[jagabo]

If you post a ~10 second clip where the problem is obvious a few people here will probably take a look at it. But it sounds like the stuttering is part of the original recording. You may not be able to fix it.

[chupacabra]

Yes I also believe it has something to do with the file itself. The stuttering happens only if there are several things moving in the image (e.g. a car driving by or people dancing near a fireplace). The stuttering doesn't stop the video but you can clearly see that there are kind of little lags (with millisecond length) during the playback.

I tried to playback the file with Windows Media Player Classic and VLC and the file stutters with both players.

[guns1inger]

It sounds like the file may have originally been NTSC and has been re-encoded to PAL very badly. There is really very little you can do to fix this. You might be able to IVTC it, but that is pretty heavy duty processing for an experienced person, let alone a beginner. I would suggest writing this one off.

[chupacabra]

Hmmmm... Regardless I post the first 30 seconds of the video so that we see what we are talking about:

http://members.chello.hu/balla.gyorgy/videos/darkskies10intro.avi

Thank you very much for your replies so far.

[jman98]

Yes I also believe it has something to do with the file itself. The stuttering happens only if there are several things moving in the image (e.g. a car driving by or people dancing near a fireplace). The stuttering doesn't stop the video but you can clearly see that there are kind of little lags (with millisecond length) during the playback.

I tried to playback the file with Windows Media Player Classic and VLC and the file stutters with both players.

Some Philips DVD players don't like packed bitstream, but it's used because AVI files seem to have the B and P frames in the wrong order and this causes a DVD player to have to read several frames into the future before it can correctly display a frame now. Packed bitstream is a way to put the frames in a logical order so the player doesn't have to read future frames. A good question is why do AVI files have the frames in the wrong order at all, but I don't know the answer to that. I have an old Philips DVD player that doesn't support packed bitstream and I notice no delays when playing AVI files, so I think that packed bitstream is rarely necessary.

The stuttering could be caused by:
A bad NTSC->PAL conversion.
Resizing of a high definition image to standard definition size.
Field order problems can cause this with MPEG video, but I don't know if AVI files can have this kind of problem because they are very different from MEPG video. I just mention it because it might be possible to be the problem.

[jagabo]

http://members.chello.hu/balla.gyorgy/videos/darkskies10intro.avi

That video was converted poorly and blend deinterlaced. You're not going to make it any better.

[chupacabra]

Thank you for downloading and watching it. Too sad it was encoded poorly.