[linuxtv-softmpeg] Re: Chroma artifacting

[Peter Urbanec <linuxtv.org.dvb@urbanec.net>]

Hi Michael,

I turned off deinterlacing and retested for the chroma problems. They 
still appear, so I am pretty sure that the chroma artifacting is not 
directly related to the deinterlacing process.

I do however suspect that the cause may be related to interlace. The 
MPEG-2 stream is MP@ML, which implies 4:2:0 subsampling. Perhaps there's 
a discrepancy between how chroma is sampled between adjacent fields? If 
the chroma is encoded on a per-frame basis and decoded on a per-field 
basis (or vice-versa) then it is possible to end up with chroma from the 
wrong point in time and space. I have previously seen such issues when 
transcoding DV25 material to MPEG2.

I'll have a read of the standard to see if I can get a clear answer on 
how the streams are supposed to be encoded.

Then again, there may be a completely different explanation...


--
   "Beauty lies in the hands of the beer holder."




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