(rabomil @ aug. 15 2005,03:11 Wrote:[quote=johnh123,aug. 14 2005,03:13]ok ive been fiddling around with this. these rules dont work.
i'm using the following 'rules' for my encodes, to keep xbox compatible, without dropping frames:
- i encode movies with a 2.35:1 aspect ratio to the full dvd width of 720 pixels.
- i encode movies with a 16:9 aspect ratio to a width of 640 pixels (this is actually the maximum width of regular tv's). i do not use anamorphic resolutions, because that really hurts the performance of the xbox. besides that, there's no significant visual gain, compared to square pixel.
- i use six file sizes: 740 mb (1/6 part of a dvdr), 1480 mb (2/6 part of a dvdr), 2048 mb (maximum iso file size), 2960 mb (4/6 part of a dvdr), 3700 mb (5/6 part of a dvdr) and 4440 mb (6/6 part of a dvdr). most movies i encode have a size of 1480 mb or 2048 mb.
- the average video bitrate stays between 1.3mbit and 2 mbit. the video bitrate appears not to be too important when it comes to compatibility with the xbox.
- the average audio bitrate is either 448 kbit lc-aac or 256 kbit he-aac. it depends on the videobitrate and the total file size whether i use lc- or he-aac.
- i use the standard avc profile, with the default settings, except for the encoding options. there i only use bidirectional prediction (b-frames, 3 b-frames in a row max). it is possible to use macroblock partitions and weighted prediction, but i prefer not to use them. cabac and deblocking are hardly usable, because this will almost certainly cause frame drops. other avc profiles gave some artifacts on my xbox (not on my pc) and do not offer options that prove to be really useful for the resolutions i use, quality wise.
compared to divx/xvid, h264/avc is a huge step forward. :thumbsup:
i have a correctly profiled (pd-xbox_hires) sharktooth profile transcode in an mp4 container using 640x272 resolution, correct for 2.35:1 dar. i set an average bitrate of 1706, well within the max on those rules specified.
streaming this over smb the movie plays for a bit in hardware overlays, but on a significant scene change it will then messup. i suspect this is occuing when it gets hit with a big keyframe on the 6279 kbps maximum bitrate.
some info on the audio track:
track # 1 info - trackid 1 - timescale 25 - duration 02:22:10.000
media info: language "und" - type "vide" - sub type "avc1" - 213250 samples
handler name: gpac iso video handler
visual stream - objecttypeindication 0x21
avc/h264 video - visual size 640 x 272 - profile main @ level 5.1
decoding buffer size 75413 - average bitrate 1706 kbps - max bitrate 6279 kbps
no stream dependencies for decoding
the only other stream is a vbr aac audo stream.
im just not sure the xbox has within itself to do this, but i'd be very happy if it could be worked around somehow.