Mediatek & XviD RC2 settings compatibility review

[Alxemi]

Hi all of you!

There was upon a time a thread (http://forum.doom9.org/showthread.php?s=&threadid=71179) about Packed Bitstream & OGM which derivates into this. (for more details read the thread). Anyway here is my little testing for the Mediatek chip, embedded in an Ascomtec 3004 player.

The source was a 592 frames long 608x256 already XviD compresed video (served to vdub via avisynth). Here are the default settings:


Adaptative Quantization ON
MPEG MATRIX: Andreas 78er
1 Pass Target Quant 2
Chroma Optimizer Enabled
Motion Search Precision 6
VHQ 1
Chroma Motion
Turbo mode ON
Max I-Frame 250
Closed GOV (when using B-Frames) ON

I just tried to reach high bitrates and low quants to force the chip. The resulting bitrate was between 1500 and 2000.
Any setting not listed is by default.

And now the test :)


1.avi
All other settings by default
PERFECT PLAYBACK

2.avi
Qpel ON
PERFECT PLAYBACK

3.avi
Qpel ON
GMC ON
NO PLAYBACK. It opens the file but only shows a couple of frames (I-frames?) and exits

4.avi
GMC ON
NO PLAYBACK. Same as before.

5.avi
B-VOPS 1 1.50 1.00
Packed Bitstream ON
PERFECT PLAYBACK

6.avi
B-VOPS 2 1.50 1.00
Packed Bitstream ON
BVOP Sensivity 25 -->to force the consecutive bframes
JERKY PLAYBACK. It seems that mediatek doesn´t like packed bitstream when more than 1 bframe is used.


7.avi
B-VOPS 3 1.50 1.00
Packed Bitstream ON
BVOP Sensivity 50 -->to force the consecutive bframes
JERKY PLAYBACK AGAIN

8.avi
B-VOPS 1 1.50 1.00
Packed Bitstream OFF
PERFECT PLAYBACK

9.avi
B-VOPS 2 1.50 1.00
Packed Bitstream OFF
BVOP Sensivity 25 -->to force the consecutive bframes
PERFECT PLAYBACK

10.avi
B-VOPS 3 1.50 1.00
Packed Bitstream OFF
BVOP Sensivity 50 -->to force the consecutive bframes
PERFECT PLAYBACK

11.avi
B-VOPS 3 1.50 1.00
Packed Bitstream ON
BVOP Sensivity 50 -->to force the consecutive bframes
QPEL ON
JERKY PLAYBACK. Again the PB

12.avi
B-VOPS 3 1.50 1.00
Packed Bitstream OFF
BVOP Sensivity 50 -->to force the consecutive bframes
QPEL ON
PERFECT PLAYBACK

13.avi
B-VOPS 4 1.50 1.00
Packed Bitstream OFF
BVOP Sensivity 50 -->to force the consecutive bframes
QPEL ON
PERFECT PLAYBACK

14.avi
B-VOPS 5 1.50 1.00
Packed Bitstream OFF
BVOP Sensivity 90 -->to force the consecutive bframes
QPEL ON
PERFECT PLAYBACK and even with six bframes in a row!!!!(show me the internals show me)

15.avi
B-VOPS 3 1.50 1.00
Packed Bitstream OFF
BVOP Sensivity 50 -->to force the consecutive bframes
QPEL ON
Max I-Frame 5
PERFECT PLAYBACK (Sometimes 4 consecutive bframes, and Max I-Frame not always respected)


So it seems that mediatek likes everythig except 3 warp-points-GMC (already known) and Packed Bitstream.

Zhnujm:
I was so sure that Packed Bitstream was enabled in my encodes, that i cannot understand how could it happen. :confused: :confused: anyway this test gives some light to me :D

Everybody:
If you want me to test a configuration/clip, just post here the settings or URL. I can give you any clip from the comparison if you want to test them in your players too.

bye

[Zhnujm]

How did you check the number of consecutive bframes ?
Im creating a test dvd with various scenes and im a bit tired of checking the number of bframes by playing all the files on my elta and see if it stutters :rolleyes:

[plazz2000]

Thanks for that, Alxemi! Great test!

I've seen similar results with my Elta 8883. If the chipset is powerful enough to decode 6 consecutive B-Frames, then surely the Packed Bitstream problem can be fixed with a future firmware upgrade?

By the way, did you copy the file to CD or DVD?

[Alxemi]

How did you check the number of consecutive bframes ?
Texas way: loking the "Show me the internals!" codec information while coding (mark-unmark-mark-unmark) :D

Weird but you don´t have to waste more time beyond the encode testing or whatever.

plazz2000: I did the test in a DVD+RW. I´ve never used CDRW in my Ascomtec, but playback problems has been reported with that media (and even with CDR). Maybe the ELTA doesnt´have that problems (just in the case they are not clones, what i think they are).

Truth is that I´m a litlle confused with the results of the test. As far as i know, Packed Bitstream exists to handle bframes in the way Divx do, and doing that to avoid problems with decoders that are expecting Divx-bframes. Then, if Mediatek is a Divx certified chip, why it only decode bframes well when they are stored in the XviD way??

Paste from crustys unofficial faq:
-'Packed Bitstream' is an option that can deliver mixed results during playback, depending on what you use for playback. It's meant to solve frame-order issues when encoding to container formats like avi that can't cope with out-of-order frames. And while it's meant to solve playback issues that occur without it, lots of people have reported playback issues with it. That goes for playing back with ffdshow, DivX 5 decoder, and several standalone (hardware) players.
Unless you know precisely what you're doing, it's best to keep it turned off until further notice. If you encounter problems with choppy playback, try turning this feature on and see if it helps.
Note: If you only play your files with the XviD codec, you never ever have to use packed bitstream

[Zhnujm]

Well, i think as DivX only supports 1 bframe the player does not expect more than 1 when packed bitstream is used. Hope that will be fixed in the new firmware, from Ascomtec,elta or whatever runs on my player :)