Best video quality supported by N800 and N810 via mplayer - Page 5 - maemo.org

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	Jaffa	2009-10-07 , 08:31
	Posts: 2,535 \| Thanked: 6,681 times \| Joined on Mar 2008 @ UK	#41

Thanks for that takla, I'll try and get a new release out soon. Probably not before the summit, unfortunately.

tablet-encode still useful with the N900, btw for either HD video, DVB recordings etc. However an "N900" preset which targets 800x480 might be a good idea :-)

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shadowjk	2009-10-08 , 05:01
Posts: 1,258 \| Thanked: 672 times \| Joined on Mar 2009	#42

Originally Posted by takla

mbd, v4mv, and trellis

Also try cmp=10:subcmp=10

The options vrc_buf_size=450:vrc_minrate=0:vrc_maxrate=1000 would seem to be redundant when using lavc as it accepts the specified bitrate as a maximum anyway, and intelligently uses less if the specified rate is not required.

Not quite. Without the vrc_*, the vbitrate is interpreted as the average bitrate across the whole file. This is to say it's equivalent to vrc_maxrate=vbitrate and vrc_buf_size=vbitrate*cliplength. This allows the bitrate to become very high in short action scenes, and stay low for the rest of the clip.
The purpose of adding the vrc_* stuff has probably been to limit short-term bitrate too, in order to avoid excessive CPU use. Removing it should improve the appearance of action scenes while risking too high CPU usage decoding them, resulting in framedrop. 450 sounds kinda low though...

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takla	2009-10-08 , 05:43
Posts: 8 \| Thanked: 8 times \| Joined on Aug 2009	#43

Thanks for the info, nice and clearly explained.

I'm not using those options at all now for encoding for N810 and haven't encountered any ill effects. I've encoded from PAL Progressive DVD and NTSC mixed Progessive/Interlaced DVD and from a wide variety of .avi .mkv .mp4 and similar. Initially I encoded quite a few with a video bitrate max set at 1000 with vbr mp3 audio....no issues so far, though 768 seems like more sensible maximum if the compression is of high quality.

Usually if I'm watching video on the N810 I'm not doing much else with it, though typically the wifi will be on, the file manager will be open in the background and sometimes I'll be transferring a large file onto it using ssh and midnight commander. I expect some people will have more going on and the vrc_* options will be more useful, but improving the compression quality is the big one.

I'll make a few encodes with cmp=10:subcmp=10 and compare. Previously I've only been using cmp and subcmp values when encoding full size high quality from DVD.

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takla	2009-10-09 , 21:20
Posts: 8 \| Thanked: 8 times \| Joined on Aug 2009	#44

After a few test encodes (and only a few, definitely not exhaustive testing here) using cmp=10:subcmp=10 offers a very significant quality increase over the tablet-encode defaults and a much faster encode time (about 20% shorter) compared to the options I proposed. I think the mbd, v4mv, and trellis options do offer slightly better quality but it's not huge and when the display size is so small it's also not important. Using cmp=10:subcmp=10 instead of mbd=2:v4mv:trell does raise the bitrate and filesize a little but this is easily limited with lavc anyway, so it looks like the best option to me.

For a new version of tablet encode I think this enhancement would be a huge benefit. I guess it may require a reworking of the bitrate calculation, which anyway produces files with far lower bitrate than specified, so that is probably no bad thing...except for the author who does the work :-)

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shadowjk	2009-10-10 , 07:19
Posts: 1,258 \| Thanked: 672 times \| Joined on Mar 2009	#45

I'd recommend retaining mbd=2 atleast. *cmp=10 is a "noise preserving" feature, which makes some videos look nicer to some people. Video quality is subjective

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takla	2009-10-10 , 10:39
Posts: 8 \| Thanked: 8 times \| Joined on Aug 2009	#46

man mencoder

cmp=<0-2000>
Sets the comparison function for full pel motion estimation

subcmp=<0-2000>
Sets the comparison function for sub pel motion estimation

mbd=<0-2> (also see *cmp, qpel)
Macroblock decision algorithm (high quality mode), encode each macro block in all modes and choose the best.
This is slow but results in better quality and file size. When mbd is set to 1 or 2, the value of mbcmp is
ignored when comparing macroblocks (the mbcmp value is still used in other places though, in particular the
motion search algorithms). If any comparison setting (precmp, subcmp, cmp, or mbcmp) is nonzero, however, a
slower but better half-pel motion search will be used, regardless of what mbd is set to

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	MountainX	2009-10-10 , 13:00
	Posts: 415 \| Thanked: 193 times \| Joined on Jun 2009 @ A place with no mountains	#47

Originally Posted by karatchov

As a reply to JustJoe asking to see "benefit of going from 480 to 600+ in resolution", I just uploaded 2 videos of the same source:
TestVideo-480-270-800bitrate.avi
TestVideo-640-360-800bitrate.avi

They both play correctly on my N800, I cant see any speed difference.

The scenes in this small videos are "active", and if mplayer is able to handle this video correctly, I think it should be able to handle any type of scene.(again I'm using 1 single pass, I THINK that with 2 passes the bitrate may "peak" on action scenes and cause some lag)

thank you. i want to try these avi files. what do i need to play them? the built-in media player say the format is unsupported.

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	Jaffa	2009-11-07 , 16:53
	Posts: 2,535 \| Thanked: 6,681 times \| Joined on Mar 2008 @ UK	#48

Right, I've released v2.30 of tablet-encode. The mbd=2:trell:v4mv options are enabled with --hq (in my testing it was ~40% longer to encode).

Also fixed in this release are 2-pass encoding, subtitles and a new N900 preset (800x480 video @ 2Mbps video). You can get some very high-quality video on an N900 from a 720p source using:

Code:

tablet-encode -p n900 --hq 'Heroes - 4x08.720p.mkv' /media/mmc2/

I've not yet tested the cmp options suggested above.

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asys3	2009-11-20 , 20:39
Posts: 101 \| Thanked: 54 times \| Joined on Jul 2007	#49

Originally Posted by Jaffa

Right, I've released v2.30 of tablet-encode. The mbd=2:trell:v4mv options are enabled with --hq (in my testing it was ~40% longer to encode).

Also fixed in this release are 2-pass encoding, subtitles and a new N900 preset (800x480 video @ 2Mbps video). You can get some very high-quality video on an N900 from a 720p source using:
Code:
tablet-encode -p n900 --hq 'Heroes - 4x08.720p.mkv' /media/mmc2/

Jaffa, tried this with my N900.
But still have some mplayer problems when playing such a file (sound is timeshifted according to the video stream).
Kmplayer says nothing, The buit-in mediaplayer denies to play the file at all.

Could you or anyone else post the correct settings for mplayer on the N900 to play videos created with tablet-encode?

That would help me (the newbie in video encoding).

Thanks a lot so far!
asys3

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	Jaffa	2009-11-20 , 21:39
	Posts: 2,535 \| Thanked: 6,681 times \| Joined on Mar 2008 @ UK	#50

Originally Posted by asys3

Jaffa, tried this with my N900.
But still have some mplayer problems when playing such a file (sound is timeshifted according to the video stream).

I haven't yet done any testing with mplayer on Maemo 5.

The buit-in mediaplayer denies to play the file at all.

Hmm, odd. That is, literally, the command I used with a 720p H264/AC3-sound video downloaded from the Internet.

It then played in the built-in Media Player without any problems.