[FFmpeg-devel] DNxHD and qmax

Baptiste Coudurier baptiste.coudurier at gmail.com
Thu Feb 2 20:39:01 CET 2012

On 02/02/2012 01:55 AM, Joseph Artsimovich wrote:
> On 02/02/2012 03:52, Michael Niedermayer wrote:
>> On Wed, Feb 01, 2012 at 11:13:46AM +0000, Joseph Artsimovich wrote:
>>> The default value for qmax in FFMpeg is 31, with FFmpeg's DNxHD
>>> encoder actually enforcing it. Now, enforcing qmax in a CBR codec
>>> makes no sence, as no one wants encoding to fail just because the
>>> minimum allowed quality specified by qmax doesn't fit into the given
>>> bitrate. The DNxHD specification actually specifies 1024 as the
>>> maximum quantization scale factor.
>>> Should I submit a patch making the DNxHD encoder ignore qmax?
>> the default value can be overriden, see libx264.c for example
>> that seems more flexible as the user then still can set it if he
>> really wants to
> That's easy to implement, however I would rather not give users ability to set qmax for CBR codecs,
> as it means giving them a rope to hang themselves on. I don't see any other uses for that feature.

early stop when searching for quantizer

Key fingerprint          8D77134D20CC9220201FC5DB0AC9325C5C1ABAAA
FFmpeg maintainer                           http://www.ffmpeg.org

More information about the ffmpeg-devel mailing list