[Matroska-devel] (no subject)

Steve Lhomme slhomme at matroska.org
Fri Mar 6 08:59:02 CET 2015


On Wed, Mar 4, 2015 at 6:14 PM, Frank Galligan <fgalligan at google.com> wrote:

> Hi Steve,
>
> Long time.
>
> Anyway, The altref frames need to have a 0 duration, but we don't need the
> 0 duration in a Block to have it signal that the altref is a non keyframe.
> We are perfectly fine having the altref frame setting the ReferenceBlock if
> it refers to another frame, signaling that the altref frame is a non
> keyframe.
>
> I just don't want muxers writing P frames with a duration of 0 to signal
> non keyframe.
>

Why is this a problem ?


> Thanks,
> Frank
>
>
> On Sun, Mar 1, 2015 at 11:57 PM, Steve Lhomme <slhomme at matroska.org>
> wrote:
>
>> On 28/02/2015 03:39, Chris Cunningham wrote:
>>
>>> + Steve, author of this addition.
>>>
>>
>> Hi everyone,
>>
>> The change was made following this discussion to handle alt-ref frames in
>> VP8 at the container level.
>>
>> https://groups.google.com/a/webmproject.org/forum/?hl=en#!
>> searchin/webm-discuss/Supported$20container$20elements/webm-discuss/
>> 9PuJWrpjE1c/76zzUjRmqpgJ
>>
>>  On Fri, Feb 27, 2015 at 6:27 PM Chris Cunningham
>>> <chcunningham at google.com <mailto:chcunningham at google.com>> wrote:
>>>
>>>     Hey Matroska!
>>>
>>>     First, let me apologize if I'm asking an answered question. The
>>>     mailing list search function is a bad link
>>>     <http://lists.matroska.org/swish/swish.cgi>.
>>>
>>>     I work on Chromium Media and we've seen a little confusion from
>>>     content creators around a line that was added
>>>     <https://github.com/Matroska-Org/foundation-source/commit/
>>> d3931e8f58898b9d673661fd7221b4704ffc917b>
>>>     to the Matroska spec
>>>     <http://www.matroska.org/technical/specs/index.html> for
>>>     BlockDuration (and whether it should be used in WebM):
>>>
>>>     "When set to 0 that means the frame is not a keyframe."
>>>
>>>     Just curious about the history/motivations for this. WebM's
>>>     container guidelines don't mention this and AFAIK WebM (de)muxers
>>>     just use ReferenceBlocks ... is there an edge-case where that
>>>     doesn't work out?
>>>
>>>     Thanks,
>>>     Chris
>>>
>>>
>>
>


-- 
Steve Lhomme
Matroska association Chairman
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