Hi there [ Please CC me since I don't subscribe to this list ]
Over the past week or so I have been running numerous tests on mjpegtools, most noteably mpeg2enc. What I am doing is taking a DV Quicktime movie exported from cinelerra 1.1.8 (.mov) and coding it to an MPEG2 stream suitable for use in standalone DVD players. I started out doing lav2yuv movie.mov | mpeg2enc -f 8 movie.m2v mplex -V -f 8 movie.m2v movie.mp2 -o movie.mpg movie.mp2 is the corresponding soundtrack (48kHz, 16 bit) in 224bps layer 2 format. I am using mjpegtools 1.6.2. This was then formed into a DVD FS using dvdauthor v0.6.9. An iso/udf was made with mkisofs 2.00 and the result written to DVD-R using growisofs from dvd+rw-tools 5.17.4.8.6. The resulting disk played fine in a Pioneer DV-344 DVD player except for one rather noticeable problem. Whenever there was moderate motion of the subject, considerable artifacts were observed. If the subject waved their arm around a blocky trail would appear, disappearing around half a second later on average. When the .m2v was played back on MPlayer 1.0.0pre1 these artifacts were not visible. I played around with many different mpeg2enc options including bit-rate, motion search radius and quality, but nothing really changed significantly. Even at "-b 8500 -q 4 -r 32 -4 1 -2 1" the artifacts remained. Looking closer at the effect on the DVD player I noticed that every 15th frame was "perfect", with things getting progressively worse with each subsequent frame. This corresponds to the maximum default GOP setting in mpeg2enc, so these must be the I frames. This suggests that there was something wrong with the intermediate P frames. I then tried forcing the MPEG2 stream to include just I frames. When played back on the hardware DVD player the result was excellent - no artifacts at all. However, it seemed the hardware player wasn't completely happy with things since it was not possible to fast forward though the resulting disk, and doing so often locked the player up (seeking to the start of a chapter unlocked it, however). I'm reluctant to blame the hardware DVD player for much of this since it's a Pioneer DV-344 which has a reputation for playing anything you throw at it. The result of all this is that it seems mjpeptools is putting something into the P frames which the hardware DVD players don't like. Software players (Mplayer, ffplay) seem quite happy with them though, which is curious. Can anyone shed any light on these observations - either in terms of ways to "fix" the P frames or to make the "I frame only" stream happy with fast forwarding in hardware DVD players? I've searched the net fairly extensively but no one seems to be mentioning this effect which makes me think that there's something else I'm missing (but which isn't documented anywhere by people making DVDs using this toolchain). It's a plainly obvious effect and makes the DVD quite unwatchable. Best regards jonathan -- * Jonathan Woithe [EMAIL PROTECTED] * * http://www.physics.adelaide.edu.au/~jwoithe * ***-----------------------------------------------------------------------*** ** "Time is an illusion; lunchtime doubly so" ** * "...you wouldn't recognize a subtle plan if it painted itself purple and * * danced naked on a harpsichord singing 'subtle plans are here again'" * ------------------------------------------------------- SF.Net is sponsored by: Speed Start Your Linux Apps Now. Build and deploy apps & Web services for Linux with a free DVD software kit from IBM. Click Now! http://ads.osdn.com/?ad_id=1356&alloc_id=3438&op=click _______________________________________________ Mjpeg-users mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/mjpeg-users
