[theora] Black borders on resized videos

Torrance torrance123 at gmail.com
Sun Aug 23 22:48:44 PDT 2009


I don't believe this to be a player problem. The borders appear in  
Quicktime (with the Xiph component), VLC, and in Firefox as an html  

I've created a (temporary) page with three example videos and the  
command I used - each displaying their black boxes.

(The videos are hosted on the wee mac mac mini in the corner of my  
lounge with a shite connection - so be patient as they download!)

The source videos were all unaltered trailers from http://www.apple.com/trailers 
  - and you can see their original sizes in the output I've provided  
too. I guess there's the possibility that Apple's h.264 encoding may  
be odd in some way. (?)

Again, I am using the latest ffmpeg2theora.macosx binary hosted at http://firefogg.org/nightly/


On 24/08/2009, at 5:09 PM, Michael Smith wrote:

> On Sun, Aug 23, 2009 at 9:31 PM, Christopher
> Blizzard<blizzard at mozilla.com> wrote:
>> On 8/22/2009 5:37 PM, Torrance wrote:
>>> P.S. I can provide examples both of the commands given and the
>>> resulting videos if necessary.
>> What are you using for a player?  Theora video is required to be at
>> sizes that are multiples of 16 pixels.  Videos not at those sizes are
>> done by having black borders and the player is supposed to crop the
>> video viewing area.  Some players don't support that.
> Just to clarify this:
> There's an internal detail of the format that means what actually gets
> encoded is a multiple of 16 pixels. There is absolutely _not_ such a
> constraint on the actual size of theora videos - any size is entirely
> valid.
> However, as Chris says - because of this internal format detail, it's
> possible for buggy decoders/players to display some of the invalid
> area.
> Mike

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