[Live-devel] H.264 via RTP - ugly artifacts

[Jesse Hemingway]

Hello,

I apologize if this is noise - my question may well have nothing to do with
Live555, but I thought I'd post here in case anyone can help me rule it
out.  It appears I'm successfully consuming H.264 via RTSP and acquiring
frames in my mediasink.

Next, I set up ffmpeg's decoder with the SPS and PPS, and then proceed to
pass all the raw NAL units from Live555 to avcodec_decode_video2(...),
adding the bytestream start code prefix and trailing zero byte (I add
0x00000001 before the raw NAL, and 0x00 after).  I've enabled debug output
in ffmpeg, and it appears to be happily decoding without errors, other than
the frequent, and perhaps expected log of the form: *concealing 900 DC, 900
AC, 900 MV errors in P frame*.  However, when I turn this into a
displayable RGBA buffer using swscale() and display the result -- there are
lots of ugly artifacts.

At certain resolutions, the I frames result in a pretty clear picture.
 In-between, only part of the image is even reasonably decoded, and with
half to 3/4 of the image being an interpolated blur.  Even the healthier
parts exhibit a regular grid of dots and major glitches in regions where
the source video has motion.

I wanted to rule out Live555 as a potential source of such trouble - does
this sound familiar to anyone?  Advice where to focus?  A relevant log
follows...

Thanks!
Jesse

LOG:

Received 24 bytes NAL type [ 7 ]
Priming buffer started
Received 4 bytes NAL type [ 8 ]
Received 14 bytes NAL type [ 1 ]
Received 3112 bytes NAL type [ 1 ]
Received 3444 bytes NAL type [ 1 ]
Received 16 bytes NAL type [ 1 ]
Received 14 bytes NAL type [ 1 ]
Received 2143 bytes NAL type [ 1 ]
Received 1498 bytes NAL type [ 1 ]
Received 16 bytes NAL type [ 1 ]
Received 14 bytes NAL type [ 1 ]
Received 2395 bytes NAL type [ 1 ]
Received 3512 bytes NAL type [ 1 ]
Received 16 bytes NAL type [ 1 ]
Received 14 bytes NAL type [ 1 ]
Received 3808 bytes NAL type [ 1 ]
Received 2966 bytes NAL type [ 1 ]
Received 16 bytes NAL type [ 1 ]
Received 14 bytes NAL type [ 1 ]
Received 1909 bytes NAL type [ 1 ]
Received 1774 bytes NAL type [ 1 ]
Received 16 bytes NAL type [ 1 ]
Received 14 bytes NAL type [ 1 ]
Received 3915 bytes NAL type [ 1 ]
Received 3859 bytes NAL type [ 1 ]
Received 16 bytes NAL type [ 1 ]
Received 14 bytes NAL type [ 1 ]
Received 3219 bytes NAL type [ 1 ]
Received 3355 bytes NAL type [ 1 ]
Received 16 bytes NAL type [ 1 ]
Received 2304 bytes NAL type [ 5 ]
Priming buffer complete
[h264 @ 0x90a2400] concealing 900 DC, 900 AC, 900 MV errors in I frame
Picture decoded
Initializing decoder frame of size: 640x480
[swscaler @ 0x8898600] No accelerated colorspace conversion found from
yuv420p to rgba.
Received 6900 bytes NAL type [ 5 ]
[h264 @ 0x90a2400] concealing 900 DC, 900 AC, 900 MV errors in I frame
Picture decoded
Received 6945 bytes NAL type [ 5 ]
[h264 @ 0x90a2400] concealing 900 DC, 900 AC, 900 MV errors in I frame
Picture decoded
Received 73 bytes NAL type [ 5 ]
[h264 @ 0x90a2400] concealing 900 DC, 900 AC, 900 MV errors in I frame
Picture decoded
Received 40 bytes NAL type [ 1 ]
[h264 @ 0x90a2400] concealing 900 DC, 900 AC, 900 MV errors in P frame
Picture decoded
...
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