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HDMI output pretty rubbish


Guest warriorscot

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Guest warriorscot

So I finally got round to trying out the HDMI to my PC monitor. Hadn't bothered because I don't have any spare HDMI cables but got a couple extra since Santa came early with a 3d blu-ray player that didn't have one.

So I hook up the Vega to the monitor and it outputs a picture however the its at low-res which I was expecting for the home screens and app drawers. However it shows up in the monitor with the edges cut off now I am going to try it on the TV downstairs later when I get the chance and see if its just the fact its a PC monitor with fairly basic electronics causing that or not. It's a 26" 1920x1200 so I wasn't expecting it to play nicely at 1024x600 but it has display lower resolutions in the past.

But what I was really bothered about was that it displays the same resolution even when playing a video and I remember reading that when playing videos the output jumps up to 1080p which plays just fine on my monitor. So what I want to work out is if the HDMI output just doesn't work or whether its something on mine and whether or not it can be fixed.

I don't even understand why it outputs low resolution at all over HDMI, the tegra 2 has enough juice to power it at higher resolutions only thing I can think of is android 2.2 just won't do it.

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Guest wipeout140

I just tested it on my Samsung TV using my HDMI cable which is normally used for my Xbox 360 and the resolution was 1920x1080 @ 24hz and i have to say all applications, home screen, and tested movie playing on the vega to TV, worked really well

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Guest trevor432990
I just tested it on my Samsung TV using my HDMI cable which is normally used for my Xbox 360 and the resolution was 1920x1080 @ 24hz and i have to say all applications, home screen, and tested movie playing on the vega to TV, worked really well

Yes me too just tried on my Sony Bravia and it played 1080p very nicely didn't try any hi-def video on it yet though cos I don't want to fill the device up.

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Yup.. My Pioneer reported 1080p24. Not sure the player can output at the correct framerate yet but it bodes well.

I just hope they support the software for 6-12 montyhs so we can get it working perfectly :)

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The problem is that it outputs 1024x600 at 1920x1080. The reason it looks so bad is that it is rescaling the 1024x600 to 1920x1080... I guess similarly for video (but I don't have enough video on the Vega to test it at the moment...)

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Guest warriorscot

Gave it a crack on the TV and it still showed cut off edges although not as bad as the monitor did it and only along the top edges its shows the whole horizontal image. Little annoying, hoping something can fix this might see if I can't do some tweaking to see what the problem is.

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Guest TeaTimeSoon

I need to get to the bottom of this.

I suggest that we should try and clarify what works and what doesn't with a little more detail - it is no good saying "I tried this and it didn't work" unless more information is provided on how the video has been formatted.

For example, MP4 streams can have both real pixel resolutions as well as anamorphic display characteristics (effectively the video may be stretched to look right on a display).

There is a good explanation of all this on the Handbrake page here:

http://trac.handbrake.fr/wiki/AnamorphicGuide

I have probably been a bit lax with the anamorphic settings when encoding some of my videos as I see that some of them are not displaying the correct aspect ratio when playing on the Vega, but apart from this they look fine on my TV (only a 26" but it is a 1080p screen). When playing media from my PC using VLC I can override the aspect ratio on playback - but the Vega is completely lacking in playback controls (other than forward back pause !) so I am not able to tweak things on the tablet.

I tried a 720p clip from Apple's HD video pages (http://http://trailers.apple.com/) and it played perfectly in every respect on both the Vega and my TV. I have not yet checked how this HD video was encoded (particularly I want to get to the bottom of the aspect ration issue) but this gives me hope that the Vega will make a good media device.

I am a bit of a video nerd and use a variety of tools for editing and transcoding, including the fabulous Avisynth - a little bit of a learning curve but immensely rewarding once over the hump.

I plan to compile a definitive set of video instructions for the Vega at some point. Details will include:

What containers work (AVI, MP4, MKV, MOV etc.)

What profiles work for some of these containers.

What codecs work (H.264/X264, H.263, DIVX/VVID etc.)

What are the bitrate limitations (globally or with specific codecs)

What pixel resolution is best for on-tablet viewing (minimising SD card storage requirements) vs. HDMI output where the maximum quality is needed for 1080p or 720p display.

Set against the previous point will be the compression level to choose (a massively compressed 1080p video will look worse than a gently compressed 720p video and the latter will put less strain on the GPU etc.)

The various issues of audio coding will also be addressed - although in general this is an easier subject to investigate and make clear. One potentially significant issue is likely to be the potential audio sync issues with higher bitrate videos and arising from transcoding from videos with variable bitrate audio (usually the only solution in the latter case is to strip out the video,

It would be nice to create a Handbrake profile for DVD ripping/ video transcoding and it would probably also be a good idea to create a script or two for Avisynth for transcoding etc.

Not sure when I can get this underway, but hope to make a start some time over the holiday period.

J

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Guest SilentMobius
So I finally got round to trying out the HDMI to my PC monitor. Hadn't bothered because I don't have any spare HDMI cables but got a couple extra since Santa came early with a 3d blu-ray player that didn't have one.

So I hook up the Vega to the monitor and it outputs a picture however the its at low-res which I was expecting for the home screens and app drawers. However it shows up in the monitor with the edges cut off now I am going to try it on the TV downstairs later when I get the chance and see if its just the fact its a PC monitor with fairly basic electronics causing that or not. It's a 26" 1920x1200 so I wasn't expecting it to play nicely at 1024x600 but it has display lower resolutions in the past.

But what I was really bothered about was that it displays the same resolution even when playing a video and I remember reading that when playing videos the output jumps up to 1080p which plays just fine on my monitor. So what I want to work out is if the HDMI output just doesn't work or whether its something on mine and whether or not it can be fixed.

I don't even understand why it outputs low resolution at all over HDMI, the tegra 2 has enough juice to power it at higher resolutions only thing I can think of is android 2.2 just won't do it.

Just to check, you are using the default video app and not rockplayer/vplayer/aplayer right? because only the default opencore video engine will output to HDMI at full res, everything else will just be doing 1024x600

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Guest warriorscot

Yeah its the default. Tried it with two different cables on my monitor and the TV its pretty annoying. Don't expect it to be much of a problem and if we ever see 2.3 I would put good money on this problem going away but it would still be nice to hook it up to the TV and get a decent video output without bits of the screen cut off.

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Guest SilentMobius
Yeah its the default. Tried it with two different cables on my monitor and the TV its pretty annoying. Don't expect it to be much of a problem and if we ever see 2.3 I would put good money on this problem going away but it would still be nice to hook it up to the TV and get a decent video output without bits of the screen cut off.

I'd be _very_ surprised if it went away with 2.3. I'd put money on it being a function of the HDMI subsystem on the tegra2 not a software thing.

I was testing with a HDMI->dvi adaptor and testing on a 1920x1080 monitor with baseline profile 1080p content played at full-res without anything cut off.

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I was testing with a HDMI->dvi adaptor and testing on a 1920x1080 monitor with baseline profile 1080p content played at full-res without anything cut off.

I think this is 1080p content, decoded to 1024 and then upscaled in hardware to 1080p. Can't prove it, but that's what it looks like when you play the (very limited) clip I have on the device (I'm waiting for SMB streaming before using it to play files).

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Guest SilentMobius
I think this is 1080p content, decoded to 1024 and then upscaled in hardware to 1080p. Can't prove it, but that's what it looks like when you play the (very limited) clip I have on the device (I'm waiting for SMB streaming before using it to play files).

I don't believe so, the clip I was using was a BBC hd test card, I could see more of the horizontal grill than I could on the Vega's screen. 600px content on a 1080p display it pretty easy to detect with horizontal bars.

Gah, edit. There is only a vertical grill on the test card, still I could see lines on the lowest level of grill when paying the video natively on my PC or via HDMI on my Vega. On the Vega screen the bottom two levels were just grey.

Edited by SilentMobius
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I don't believe so, the clip I was using was a BBC hd test card, I could see more of the horizontal grill than I could on the Vega's screen. 600 PDF content on a 1080p display it pretty easy to detect with horizontal bars.

Cool. I haven't done enough testing here to know.

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Guest David.m
I need to get to the bottom of this.

I suggest that we should try and clarify what works and what doesn't with a little more detail - it is no good saying "I tried this and it didn't work" unless more information is provided on how the video has been formatted.

For example, MP4 streams can have both real pixel resolutions as well as anamorphic display characteristics (effectively the video may be stretched to look right on a display).

There is a good explanation of all this on the Handbrake page here:

http://trac.handbrake.fr/wiki/AnamorphicGuide

I have probably been a bit lax with the anamorphic settings when encoding some of my videos as I see that some of them are not displaying the correct aspect ratio when playing on the Vega, but apart from this they look fine on my TV (only a 26" but it is a 1080p screen). When playing media from my PC using VLC I can override the aspect ratio on playback - but the Vega is completely lacking in playback controls (other than forward back pause !) so I am not able to tweak things on the tablet.

I tried a 720p clip from Apple's HD video pages (http://http://trailers.apple.com/) and it played perfectly in every respect on both the Vega and my TV. I have not yet checked how this HD video was encoded (particularly I want to get to the bottom of the aspect ration issue) but this gives me hope that the Vega will make a good media device.

I am a bit of a video nerd and use a variety of tools for editing and transcoding, including the fabulous Avisynth - a little bit of a learning curve but immensely rewarding once over the hump.

I plan to compile a definitive set of video instructions for the Vega at some point. Details will include:

What containers work (AVI, MP4, MKV, MOV etc.)

What profiles work for some of these containers.

What codecs work (H.264/X264, H.263, DIVX/VVID etc.)

What are the bitrate limitations (globally or with specific codecs)

What pixel resolution is best for on-tablet viewing (minimising SD card storage requirements) vs. HDMI output where the maximum quality is needed for 1080p or 720p display.

Set against the previous point will be the compression level to choose (a massively compressed 1080p video will look worse than a gently compressed 720p video and the latter will put less strain on the GPU etc.)

The various issues of audio coding will also be addressed - although in general this is an easier subject to investigate and make clear. One potentially significant issue is likely to be the potential audio sync issues with higher bitrate videos and arising from transcoding from videos with variable bitrate audio (usually the only solution in the latter case is to strip out the video,

It would be nice to create a Handbrake profile for DVD ripping/ video transcoding and it would probably also be a good idea to create a script or two for Avisynth for transcoding etc.

Not sure when I can get this underway, but hope to make a start some time over the holiday period.

J

A handbrake profile would be great would be worth a beer if you could get one correctly finished

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Guest SilentMobius

Ok I've been testing some more and made a small video from a 1080p test image I found.

http://dl.dropbox.com/u/6553908/1920x1080overscantl7.m4v

I think in my case it _is_ displaying at 1080p but with no overscan, therefore its trying to fit 1080p content is a slightly smaller frame I can see each line but I can see that the lines move in and out of phase (and I have black borders all around)

So, I wonder if the Tegra 2 userspace libs have overscan control somewhere

Edited by SilentMobius
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Guest iserlohn
Ok I've been testing some more and made a small video from a 1080p test image I found.

http://dl.dropbox.com/u/6553908/1920x1080overscantl7.m4v

I think in my case it _is_ displaying at 1080p but with no overscan, therefore its trying to fit 1080p content is a slightly smaller frame I can see each line but I can see that the lines move in and out of phase (and I have black borders all around)

So, I wonder if the Tegra 2 userspace libs have overscan control somewhere

With digital, overscan is usually controlled at the display, not at the signal source.

Used the stock player to play 1080p basic profile h.264 video and the output is pixel perfect on the display.

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Guest SilentMobius
With digital, overscan is usually controlled at the display, not at the signal source.

Used the stock player to play 1080p basic profile h.264 video and the output is pixel perfect on the display.

I'm not sure that's true for HDMI, if you google for "hdmi overscan black border" you'll see a number of people with PC's having problems with 1080p content failing to display 1:1 on a 1080p monitor where the solution was found in the video card config app.

Though if you're getting pixel perfect 1:1 1080p I think that answers the question of whether the Vega is capable of true 1080p output, which is great.

I've been greping through the source for the nvidia developer android build and found found something interesting. It seems opencore and stagefright both parse an overscan_appopriate_flag from m4v containers and avc streams. I wonder if that's passed all the way through to the nvidia userspace binary blobs that handle HDMI out. Looking at the source of libx264 it seems like overscan=show should be passed through to the display to ask it to skip any over/underscan compensation. Alas I haven't found an easy way to produce a test file what would have this flag set .

Edited by SilentMobius
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Ok I've been testing some more and made a small video from a 1080p test image I found.

http://dl.dropbox.com/u/6553908/1920x1080overscantl7.m4v

I think in my case it _is_ displaying at 1080p but with no overscan, therefore its trying to fit 1080p content is a slightly smaller frame I can see each line but I can see that the lines move in and out of phase (and I have black borders all around)

So, I wonder if the Tegra 2 userspace libs have overscan control somewhere

Your video is exactly the same for me (1080p TV set to display dot-by-dot - i.e. no overscan) and I get phase lines and black borders. Interestingly, media player classic - home cinema on the PC won't play the file (I suspect because it doesn't have any audio).

I think the reason there are black bars at the top and bottom on the Vega is that 1024 x 600 isn't exactly 16:9 (1024x576 would be).

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Guest SilentMobius
Your video is exactly the same for me (1080p TV set to display dot-by-dot - i.e. no overscan) and I get phase lines and black borders. Interestingly, media player classic - home cinema on the PC won't play the file (I suspect because it doesn't have any audio).

I think the reason there are black bars at the top and bottom on the Vega is that 1024 x 600 isn't exactly 16:9 (1024x576 would be).

On the Vega yes, but I'm getting a black frame on my 1080p monitor as well, and that is native 16:9

Aoc seem to be awful at providing manuals so I can't see if there are any overscan settings available at the monitor end. But I'd be supprised if that was the problem

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On the Vega yes, but I'm getting a black frame on my 1080p monitor as well, and that is native 16:9

My black frame is on my Pioneer LX508 which is 100% good with all other sources at 1080p dot-by-dot (i.e. the vega is overscanning the display in some way). It's the Vega not displaying the video correctly in some way...

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Guest ricwales1
My black frame is on my Pioneer LX508 which is 100% good with all other sources at 1080p dot-by-dot (i.e. the vega is overscanning the display in some way). It's the Vega not displaying the video correctly in some way...

Some Pioneer plasma have overscan setting in menu system. Try adjusting this, see if this helps.

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Some Pioneer plasma have overscan setting in menu system. Try adjusting this, see if this helps.

No... it's set to dot-by-dot mode which is pixel perfect... I work in digital video so am anally retentive about such things... :)

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Guest ricwales1
No... it's set to dot-by-dot mode which is pixel perfect... I work in digital video so am anally retentive about such things... :)

Seeing as the tv menu system has been checked I guess that's me told lol

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Guest warriorscot
so am anally retentive about such things

That sounds really painful.

It seems there are a few unusual presentations of the vega video output. If only I could force it to output 1080p all the time but according to the TV an monitor it isn't and I think my problem is that Samsung monitors and TVs don't play well unless you give them video in the correct resolution to start with. Going to try it on my brothers Evesham tomorrow see as all the other TVs or monitors in the house don't have HDMI and I don't have any adapters for it.

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