[FFmpeg-devel] [PATCH 4/5] aptx: implement the aptX HD bluetooth codec

Carl Eugen Hoyos ceffmpeg at gmail.com
Mon Jan 8 15:19:23 EET 2018


2018-01-08 13:37 GMT+01:00 Hendrik Leppkes <h.leppkes at gmail.com>:
> On Mon, Jan 8, 2018 at 1:27 PM, Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:
>> 2018-01-08 11:32 GMT+01:00 Hendrik Leppkes <h.leppkes at gmail.com>:
>>> On Mon, Jan 8, 2018 at 1:38 AM, Rostislav Pehlivanov
>>> <atomnuker at gmail.com> wrote:
>>>>
>>>> That's okay - for encoding switch the profile depending on both the
>>>> avctx->profile setting and the samplerate and list all supported
>>>> samplerates for all profiles in the AVCodec structure. We do something
>>>> similar in the AAC encoder where we pick different settings depending on
>>>> the profile and change the profile depending on the settings listed.
>>>> If there's an overlap, pick a sane default unless the user forces a profile
>>>> using profile:a. If forced and the samplerate isn't supported - error out
>>>> and let the user know.
>>>> For decoding set the profile via the demuxer. There doesn't have to be just
>>>> one demuxer for a codec. If there are major changes in how you parse
>>>> profiles go ahead and make a new one which sets the codec ID and the
>>>> profile.
>>>>
>>>
>>> I don't think there is any precedent for "profile" being mandatory for
>>> a decoder to work, so that might be iffy. Decoders usually set
>>> profile, don't require it.
>>> ie. from the docs:
>>> * - decoding: Set by libavcodec.
>>>
>>> There is plenty precedent for using "codec_tag" however, so that may
>>> be a better choice - and can hold the tag from the "container" as-is
>>> as well.
>>
>> While I don't understand why even having more than one codec_id for
>> the same codec (which afaiu isn't the case here) would be an issue, I
>> don't think we should invent codec_tags unless necessary.
>>
>
> We're not inventing them if they are a copy from the container
> bitstream tag field.

I completely agree!

Is there a container bitstream tag field in this case?

Carl Eugen


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