Hi, Michael Niedermayer wrote: > Hi > > On Mon, Jan 01, 2007 at 08:37:00PM +0000, Paul Richards wrote: > >> On 01/01/07, Rich Felker <dalias at aerifal.cx> wrote: >> >>> On Sun, Dec 31, 2006 at 08:09:54PM +0000, Paul Richards wrote: >>> >>>> On 31/12/06, Michael Niedermayer <michaelni at gmx.at> wrote: >>>> >>>>> On Sun, Dec 31, 2006 at 05:56:11PM +0000, Paul Richards wrote: >>>>> >>>>>> And on a deeper level.. >>>>>> >>>>>> Why is all this special packing of the output from theora_encode_***() >>>>>> into the extradata required? I naively assumed that any packing like >>>>>> this would be the responsibility of the muxer... >>>>>> >>>>> no of course not, just think about this for a moment, should the avi >>>>> >>> muxer >>> >>>>> contain code to repackage theora, vorbis, ... headers? then what about >>>>> matroska, nut, asf, mov, mp4, ... ? should every muxer contain >>>>> >>> (duplicated) >>> >>>>> code to pack all the codec specific xiph headers into a single packet? >>>>> >>>>> and then after you duplicated that code in every muxer, you will have to >>>>> add code to every corresponding demuxer to undo it otherwise you cannot >>>>> copy a stream between 2 containers witout reencoding ... >>>>> >>>>> simply putting the (de)packaging code into the 2 or 3 xiph codecs is >>>>> >>> much >>> >>>>> easier ... >>>>> >>>>> >>>> In that case shouldn't there be a function in libtheora to concatenate >>>> all of the "extradata" packets together in a container-insensitive >>>> way? >>>> >>> yes, there certainly should be. unfortunately the xiph people, in >>> their infinite wisdom, are outwardly hostile to container-insensitive >>> things and want to make their codecs as painful as possible to use >>> with non-ogg containers. >>> >>> btw, is there a reason you want to use theora so much? it's not a good >>> codec at all.. >>> >>> >> I have two reasons. >> >> 1) I want to show some support for a patent-free video codec. >> >> 2) Theora was quite good in a few basic tests I ran here. Compared >> against ffmpeg's "mpeg4" codec at 400kbit CBR, theora was clearly >> better. >> > > > dont forget to set reasonable options for encoding! > (-flags +mv4+aic+trell -mbd rd -cmp 2 -subcmp 2 -pass 1/2) > -flags qprd is also worth a try > and ensure that you set the vbv buffer size in all codecs to the same > value, and DONT mess with -bt > > also it is _very_ important to use postprocessing on the decoder side for > mpeg4 asp (theora and h.264 have their own "postprocessing" in loop filter > build in) mplayer -vf spp=X or -vf pp is something you could try > > > >> Compared against ffmpeg's "h264" (libx264), there was no >> clear winner (part of the problem was that I couldn't get h264 to >> > > the default options for x264 encoding with ffmpeg are VERY bad, there > should be some recommanded command line parameters for ffmpeg-x264 > somewhere i think (no i dont remember where ...) > > [...] > > > ------------------------------------------------------------------------ I too had some difficulty finding out what parameters I should have used for higher quality output. It would be nice if there were a few well-documented parameters, such as -hq or something along those lines that turned on a good set of parameters to optimize quality over speed. Similarly this would be nice for other codecs as well (i.e. MPEG2). -Aaron
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