Comments on: Converting 16:9 content to QCIF ? http://mvstreaming.com/converting-169-ratio-content-to-qcif/ Demystifing mobile video streaming - I hope. Thu, 03 Jul 2008 19:42:46 -0400 http://wordpress.org/?v=2.8.5 hourly 1 By: weeklymg http://mvstreaming.com/converting-169-ratio-content-to-qcif/comment-page-1/#comment-4 weeklymg Mon, 21 May 2007 05:55:29 +0000 http://mvstreaming.com/converting-169-ratio-content-to-qcif/#comment-4 It takes 2 or 3 passes to do it right. If you don't know the dimensions you need to do a pass with ffmpeg or another program to parse the original dimensions (w and h) from the output. Then you need a pass without setting the size but setting padtop and padbottom to p, where 4(h + 2p) = 3w. And I think the default value for padcolor is black, which should be fine. Then you have a video with a 4:3 aspect which you transcode to 3gp in another ffmpeg pass using -s qcif. By the way, I haven't had much luck with Darwin streaming on mobile. The presence of a hinted audio track caused weird and ugly effects on the mobiles I tested with. I saw the same problem with streams from the site www.zoovision.com. The site eyeka.com seems to deal with this issue by building their own J2ME player and only showing the streaming links to their player. I don't have a phone which supports their player, though. One other issue which could block you is the operator. See this cached page for someone's test results (though note that there's what I hope is a typo - the rtsp port is 554, not 551): http://tinyurl.com/2z37l9 It takes 2 or 3 passes to do it right. If you don’t know the dimensions you need to do a pass with ffmpeg or another program to parse the original dimensions (w and h) from the output. Then you need a pass without setting the size but setting padtop and padbottom to p, where 4(h + 2p) = 3w. And I think the default value for padcolor is black, which should be fine. Then you have a video with a 4:3 aspect which you transcode to 3gp in another ffmpeg pass using -s qcif.

By the way, I haven’t had much luck with Darwin streaming on mobile. The presence of a hinted audio track caused weird and ugly effects on the mobiles I tested with. I saw the same problem with streams from the site http://www.zoovision.com. The site eyeka.com seems to deal with this issue by building their own J2ME player and only showing the streaming links to their player. I don’t have a phone which supports their player, though.

One other issue which could block you is the operator. See this cached page for someone’s test results (though note that there’s what I hope is a typo – the rtsp port is 554, not 551): http://tinyurl.com/2z37l9

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