mplayer (Leitmotiv and one other build) often have severe problems with mp4 videos. I don't think my AmigaOne is too slow, because these videos may play okay for 3 minutes, and then lose audio sync. Three minutes is also often the limit, it probably will be 100% fine if this does not happen before or at 3 minutes. I'm not sure if it's the video or the audio codec that is decisive, but get the higher quality videos from YouTube and you will see this quite soon.

Anyone have a clue what is wrong here? Actually I would like to hear if mplayer does this in other operating systems, apart from considerably more powerful systems that might circumvent the problem by mere calculation power. I have installed mplayer on the linux side as well, but it never worked properly and it has gone downhill with (any) updates.

Other video formats do not show these symptoms.

Last edited by Thematic on 12-Mar-2009 at 10:36 PM.

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@Thematic

MP4 is a container. What codec has been used? If it's h264 then AmigaOne can have problems with that file. Try to play with frame skipping, run video without sound. Maybe file is broken? Try forceidx switch.

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@opi

Yes, exactly. Typically H.264. video and AAC audio. Decoding the audio to a wav file prior to playback helps, but shouldn't be necessary.

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@Thematic

Do you have ffmpeg handy?

do ffmpeg -i source.mp4

See what bitrate it's encoded with, then

ffmpeg -i source.mp4 -ar 22050 -b 750000 output.mpg

(750000 is a decent value if orginal bitrate is ~1000kbits)

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@Thematic

This is excactly why someone (TM) should look into doing motion compensation and image reconstruction (as well as color space conversion to the frame buffer, of course) inside the GPU:

http://escher.elis.ugent.be/publ/Edocs/DOC/P107_088.pdf

There IS potential here, especially since there is no need for copying data back to system memory between those operations.

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@olegil

Quote:

This is excactly why someone (TM) should look into

Like you yourself.

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@Thematic

I've had similar under linux with varying videos so it's not exclusive to OS4 version. I don't think 3D graphics accelleration is working for AmigaOne linux PPC so that may be the commeon problem.

Incidentally mplayer works fine from the commandline in linux it just goes wobbly (for me) from the gui, mainly audio issues with ALSA.

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@Tomppeli

Quote:

Tomppeli wrote: @olegil Quote: This is excactly why someone (TM) should look into Like you yourself.

Preferably someone who knows shaders

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This weeks pet peeve:
Using "voltage" instead of "potential", which leads to inventing new words like "amperage" instead of "current" (I, measured in A) or possible "charge" (amperehours, Ah or Coulomb, C). Sometimes I don't even know what people mean.

@Thematic
Use framedrop

@broadblues

With linux mplayer I have tried to specify a driver that doesn't use OpenGL, the response is different, but it won't work.

@Tomas

Framedrop is useful for large resolution video streams, but when a 384 by 288 H.264 vid is giving trouble, it just goes massively wrong and won't keep audio sync. Then if I use hardframedrop, I get about 0.3 fps. Perhaps the codec is so complex, that you can enjoy 2 or 3 minutes of flawless decoding before encountering troublesome frames. I haven't looked, but it does seem weird.

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@Thematic

I'm not in Amiga programming but I'm a programmer so maybe these two little questions can help finding the priblem:

1) Do you see a great increasing usage of resources during the video Playback? (RAM is the first thing to check)

2) Is the audio-video synch loosing slowly or is it rather a "from a moment to the next" instantaneous thing?

3) Could you describe more verbosely what is happening to the video playback?

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@ErikBauer
Quote:

RAM is the first thing to check

RAM... that's it! I tried to view this 16 MB file from the RAM disk, and that was asking too much. From ext2 filesystem I could play at 2x speed, sound and all, and the audio was in sync from start to end, with a 3 frame margin.

It WAS a simple solution.

Last edited by Thematic on 12-Mar-2009 at 10:35 PM.

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@Thematic

Glad to have been of some help..
And yes! Unsolvable problems mostly DO have a simple solution (In informatic at least)

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Check my Amiga gameplays (ITA)!

@Thematic

It's really questionable reading a file from Ram disk would be *that* slow (compared to hard drive). Even with an unoptimized ram-handler, that doesn't explain it.

@Fab

Empirical evidence shows that it (repeatedly) fails with RAM disk and works from ext2 partition. Without it, I would have likely agreed with you.

However, it also seemed to work from FFS (compatible, 512 bytes per block) partition. There were 500 buffers.

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@Thematic

We DO believe you. But it IS weird. Positively Platypus.

_________________
This weeks pet peeve:
Using "voltage" instead of "potential", which leads to inventing new words like "amperage" instead of "current" (I, measured in A) or possible "charge" (amperehours, Ah or Coulomb, C). Sometimes I don't even know what people mean.

@Thematic

How much ram is being used to play this? Is it forceing the ram disk to swap out?

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@broadblues

No. 4.0, no swapping.

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: AmigaOneXE (unmod.) 750FX/512 MB +stuff & AmigaOS 4.(0|1)
: A1200/68060&96MB/SCSI/EM1200-Voodoo3 & OS 3.5
: A500/1MB
: Pegasos (ff) 512 MB & MorphOS
Praise seitan.

Hmm that is odd.. I have never had any problem playing back video files from ram.
I use OS 4.1 on the sam though.

@Thematic

Quote:

FFS (compatible, 512 bytes per block) partition

512 bytes per block on FFS??? Did you mean SFS?

I noticed that, if I have OWB running at the same time, mplayer is likely to be slow... may be the Javascript engine...

Last edited by mwoof on 18-Mar-2009 at 01:15 AM.
Last edited by mwoof on 18-Mar-2009 at 01:11 AM.

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