Interlaced encoding / Standalone test

[amango]

I just encoded some clips to test if my standalone player (Medion 7457, Mediatek-based chipset) can play interlaced xvid-clips.

It DOES play interlaced xvid files. However, there is a problem: On every clip I tested the output is field-shifted on the TV. The effect is the same if I watch an MPEG2-clip that was encoded with wrong field parameters ("buttom field first" instead of "Top field first" for example). Looks funny (jitter).

I also tested the same clips with DIVX 5.1.1. Here I can select "Top field first" which is very important. In this case the standalone is playing the interlaced DIVX-files fine without errors.

I think we need also this "Top field first" checkbox in XVID. Is there another way to solve this problem?

[trbarry]

FWIW, video sourced HDTV also usually seems to be top first. But I haven't tried it that way in Xvid.

- Tom

[bREAkDoWN]

Hi!
If you look at this post of mine http://forum.doom9.org/showthread.php?s=&threadid=67782 you'll see that i have been in the same situation as you, and you'll find a good workaround too.
Anyway, i still hope that a field priority option will be included in a future release of xvid.

btw: which chipset is in your standalone mpg4 player?
I have got one using the first ESS chipset and i must say that for interlaced contents, xvid works quite better on it than latest divx.

bye!

[begu]

How about b-frames?
Can the interlaced content be encoded with 1 or more b-frames and then be played back by mediatek chip? (how many it will decode?)

And what about other settigns, qpel, gmc, will they work with mediatek?

Also: what about very high bitrates together with interlaced, b-frames etc.? For example 7000 kbps and 2 bframes?

Try some virtual dub filters to adjust the field order, when encoding.

[amango]

@bREAkDoWN

That worked great. I edited the AVISynth-script and added " doubleweave.selectodd" at the buttom. The output on the TV was perfect now.

@begu

B-Frames with interlaced material works on the Mediatek-chipset. I encode usually with 3 B-Frames and a fixed quantizer (1 Pass-quantizer 3), so I have sometimes very high bitrates in my avi's. I encoded an anime-opener yesterday (X-OVA) and some scences goes up to 8000 KBit (average was 5600 KBit). You can also add QPEL but not GMC (not at the moment, this should be fixed with a firmware-update).

I burned the file on DVD-RW, because on CDR the player can't read those high bitrates. The playback was smooth without any stutter.

However... I think that XVID/DIVX works best with progressive content. If you want to encode interlaced videos, you need much more bitrate. If you reach 8000 KBit with XVID in some scenes, it will look better if you use MPEG2 for this material.

[bREAkDoWN]

@amango:
I'm glad it worked..

again btw: I've just realized that i have asked you which chipset was inside your player, while you had written it clearly at the beginning of your message :D My avatar has never been more appropriate.. doh! :p

[begu]

Originally posted by amango
@bREAkDoWN

That worked great. I edited the AVISynth-script and added " doubleweave.selectodd" at the buttom. The output on the TV was perfect now.

@begu

B-Frames with interlaced material works on the Mediatek-chipset. I encode usually with 3 B-Frames and a fixed quantizer (1 Pass-quantizer 3), so I have sometimes very high bitrates in my avi's. I encoded an anime-opener yesterday (X-OVA) and some scences goes up to 8000 KBit (average was 5600 KBit). You can also add QPEL but not GMC (not at the moment, this should be fixed with a firmware-update).

I burned the file on DVD-RW, because on CDR the player can't read those high bitrates. The playback was smooth without any stutter.

However... I think that XVID/DIVX works best with progressive content. If you want to encode interlaced videos, you need much more bitrate. If you reach 8000 KBit with XVID in some scenes, it will look better if you use MPEG2 for this material.
Thanks so much.
I know that interlaced video takes very much bitrate compared to progressive. I have sigma's xcard, that can't decode b-frames in interlaced content (maybe with .mp4 container, I haven't tried).

I encode generally 5000-8000 kbps for interlaced PAL 720 x 576 video.
Maybe with b-frames, I would get better quality, or can use lower bitrate.

[symonjfox]

Originally posted by amango
However... I think that XVID/DIVX works best with progressive content. If you want to encode interlaced videos, you need much more bitrate.I don't think so. Most of us say it's better with progressive video, just because PC monitors are progressive, and interlaced material have to be deinterlaced to be seen decently. But IMO it's better to stay as the original material is.
So Progressive -> Progressive and Interlaced -> Interlaced.
The increase of bitrate of an interlaced encode isn't so high, and, if you use bitrates > 2000 kbs on standard resolutions, it's better to keep it interlaced (if the source is).
I just finished a test from an interlaced DVB channel, I reduced the bitrate from 8000kbs mpeg2 (704*576, 4:3) to 1500 Xvid interlaced (704*576 4:3). The quality of the final encode is great, you can't distingue it from the original (I'm afraid the field order is wrong, I have no standalone to test).

ATM there are just 2 problems:
1- Using Xvid, you can't select the field order, so you have to manually edit your avisynt script, or use Divx.
2- 3ivx decoder and other mp4 decoders, may have troubles decoding interlaced material. Let's wait next releases!