Hi,
I try to use the video tag to post videos on my blog
I'm using ffmeg2theora to transcode videos in theora
Resolution of 320x240 pixels and constant bitrate (CBR) of ~400 kbps
seems to be ok for publishing on my blog.
I've read that CBR is a better choice than VBR for web publishing
regarding the way TCP/IP works.
("In TCP it takes a while for a connection to increase its bandwidth.
(And by ?a while? I mean ?not that long? but it?s long enough to
affect the low latency connection that we want for this use case"
http://hacks.mozilla.org/2009/09/theora-1-1-released/ )
Am i wrong ?
I wander if the --two-pass option in ffmeg2theora is useful or not,
since the bitrate (and then the file size) is fixed. Can i expect a
better quality or is it a waste of time in CBR ?
Thanks in advance
2010/2/26 thibaut bethune <thibaut.bethune at gmail.com>:> Hi, > > I try to use the video tag to post videos on my blog > > I'm using ffmeg2theora to transcode videos in theora > > Resolution of 320x240 pixels and constant bitrate (CBR) of ~400 kbps > seems to be ok for publishing on my blog. > > I've read that CBR is a better choice than VBR for web publishing > regarding the way TCP/IP works. > ("In TCP it takes a while for a connection to increase its bandwidth. > (And by ?a while? I mean ?not that long? but it?s long enough to > affect the low latency connection that we want for this use case" > http://hacks.mozilla.org/2009/09/theora-1-1-released/ ) > Am i wrong ? > > I wander if the ?--two-pass option in ffmeg2theora is useful or not, > since the bitrate (and then the file size) is fixed. Can i expect a > better quality or is it a waste of time in CBR ? > > Thanks in advance >-- Internet est con?u avec des formats ouverts. Afin de n'exclure personne et que vos informations restent lisibles dans le futur, merci de ne joindre que des fichiers dans un format ouvert : rtf, odt, pdf, html... Logiciel libre et format ouvert : essayez la suite bureautique OpenOffice http://www.framasoft.net/article472.html En savoir plus : http://fr.wikipedia.org/wiki/Alternatives_ouvertes_aux_formats_ferm?s
thibaut bethune wrote:> I try to use the video tag to post videos on my blogcool.> I've read that CBR is a better choice than VBR for web publishing > regarding the way TCP/IP works.Yes, but there is no such thing as CBR. The equivalent of CBR in video is buffer-constrained bitrate control, which makes sure that a user with only K seconds of buffer will be able to play through the file while downloading it at the target bitrate.> I wander if the --two-pass option in ffmeg2theora is useful or not, > since the bitrate (and then the file size) is fixed. Can i expect a > better quality or is it a waste of time in CBR ?Two-pass is useful when you are doing "CBR". It should improve the overall quality of the result. When doing VBR (i.e. constant-quality), two-pass is not helpful. --Ben -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 198 bytes Desc: OpenPGP digital signature Url : http://lists.xiph.org/pipermail/theora/attachments/20100317/dff5d737/attachment.pgp