Help with video compression, encoding, and compatibility

[Roxxi]

Hi everyone, I'm new to this forum, and new to a lot of this video stuff in general, so please keep things simple with me. =)

I bought an MP4 recently, and I've tried to put some avi videos in them. Many of them work, but some of them don't. They're either jerky, or the motions slow a bit, falling out of sync with the sound (only on my mp4 though; on my laptop they play just fine.) I've tried several things, most of which I don't remember since I was blindly testing things on processing and conversion programs - and almost nothing works. I'm hoping to get some help here to fix this problem, and if possible I'd also appreciate suggestions for the best settings on Virtual Dub, or any other program you might suggest.

As I already said before, I'm extremely new to this and will need clear, detailed instructions. Live help would be nice too (we could reply to each other more quickly), if you have gmail chat or instant messengers, but not everyone is comfortable sharing their email with strangers, so if that's the case, I'd be happy with replies to this post or PMs as well.

Thanks in advance. =)

p.s.: Some parts of videos with dark scenes look patchy on my mp4. Is there a way to fix this?

[guns1inger]

First things first - what sort of MP4 player ? These can range from iPods etc, down to cheap little Chinese players that don't even play true MP4 video.

Secondly, what, if any, software came with the player ?

[Roxxi]

It's an Apia VX787 (approximately 100 USD.) I bought it in Taiwan, and when I googled the brand name the sites that came up in the results were all in Chinese, so I'm assuming it's not known internationally, although it looks very similar to, if not the same as, the Onda VX787.

There's a video converter (along with Directx9 and the driver folder, which I don't know what to do with) in the little CD that came with it. Anyway, the video converter is called just that - Video Converter. And it doesn't work, at least when I load a file, nothing happens when I click on the "Begin" button.

[Bjs]

Try mediainfo or gspot on one that plays fine and then do the same check on the problematic clips and look for differences in encoding ... the problem should be easy enough to spot .

General rule : A pc will play anything provided codecs for decoding are installed ... other playback devices require audio / video to be created using specific settings in order to work correctly.

As for your PS ... yes, it's called "Re-encoding"

[Roxxi]

I tried what you suggested but, well, I can't really understand the results. The first screencap is of the video that plays correctly on my player, and the second is the "problematic" one. When I downloaded them, neither of them actually played well. After resizing and re-compressing the first one, the problem was solved, but applying the same steps to the second video did not help.

[filmboss80]

From the GSpot images, I can see that both have packed bitstreams. Some (but not all) players choke on that. You can change that with MPEG4 Modifier (https://www.videohelp.com/tools/MPEG4_Modifier).

Also, your second file has AC3 audio. I don't know if that's a big issue, but Divx / Xvid usually have an mp3 audio stream.

[Roxxi]

I tried your first suggestion, but that isn't it... I'm still having the same problem without the packed bitstream.

How would I change the audio?

[poisondeathray]

You can use virtualdub to re-encode just the audio, select direct stream copy for the video

Other possibilities are your portable player might:

1) like fourcc DivX but not XviD
2) only accept smaller dimensions (the 1st video frame dimension is smaller)
3) have problems with 2 or more consec b-frames

Many portable players are finicky. If the provided software doesn't work, be prepared to do a whole bunch of testing until you figure out compatible settings