Some files cause smeared artifacts

Some files cause smeared artifacts

Ritratto di jamesterm
jamesterm
Gio, 31/03/2011 - 12:27

I have attached a raw annex-b h264 file that contains a 960x720 video. When using the sample decode on this file, the YUV output shows smeared artifacts as if it never found any good I-frames.

I have about 65-75% confidence in the validity of the dump itself, and I'll continue to pursue verifing it. The original source (MP4 avcc) has been confirmed to be correct and does not produce these artifacts.

I have used this same technique on other MP4 clips with success, but so far the two clips I've found that exhibit this symptom are cartoonish and most likely have a very high compression ratio.

So now it boils down to either the avcc->annexb conversion (in my code)has a bug, or if this dump is valid, there may be somenew stress presented to the decoder to exhibit symptom. I am hoping to pinpoint which it is by the end of the day. (I'll post back once I know)

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Ritratto di jamesterm
jamesterm
Gio, 31/03/2011 - 13:07

Here is another file... this one is real footage and is 320x192 (180 cropy). The sample decode will generate 127 frames. Hopefully this will give some contrast in comparison to the first file.

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Ritratto di jamesterm
jamesterm
Gio, 31/03/2011 - 14:50

Ok I am suspecting the problem is with the AVCC->Annex B conversion... Testing raw dump with VLC yields main error: Invalid PCR value in ES_OUT_SET_(GROUP_)PCR.

For now I'll assume it is a problem with the conversion, and i'll update once I know for sure.

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Ritratto di Admin
Admin
Gio, 31/03/2011 - 15:21

Hi,

We did a quick test here on our side also. The elementary stream clips you provided definitely seem broken. For instance, the artifacts are clearly visible when playing/analyzing the stream using Elecard StreamEye or XMuxer Pro.

Regards, Petter

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Ritratto di jamesterm
jamesterm
Ven, 01/04/2011 - 10:36

Yes,it turns out some of the frame packetswere being truncated (e.g. not adding the SPS PPS size into consideration)... I have fixed this problem within my code. Thanks for testing. Next Time, I have 3 different test tools in place to confirm failure, before it needs to be escalated here. ;)

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