[FFmpeg-devel] [PATCH+RFC] AVFrame for audio

[Baptiste Coudurier]

On 07/12/2010 02:32 PM, Justin Ruggles wrote:
> Hi,
>
> Baptiste Coudurier wrote:
>
>> On 7/11/10 9:11 AM, Justin Ruggles wrote:
>>> Michael Niedermayer wrote:
>>>
>>>> On Sun, Jul 11, 2010 at 11:33:25PM +1000, Peter Ross wrote:
>>>>> On Sun, Jul 11, 2010 at 11:12:56AM +0100, M?ns Rullg?rd wrote:
>>>>>> Peter Ross<pross at xvid.org>   writes:
>>>>>>
>>>>>>> Hi,
>>>>>>>
>>>>>>> To prototype use of audio in AVFrame, I have modified the PCM encoder/decoder
>>>>>>> and addded new public lavc functions.
>>>>>>> [...]
>>>>>>> +/**
>>>>>>> + * Encode an audio frame from samples into buf.
>>>>>>> + *
>>>>>>> + * @param avctx the codec context
>>>>>>> + * @param[out] buf the output buffer
>>>>>>> + * @param[in] buf_size the output buffer size
>>>>>>> + * @param[in] frame the input buffer containing the samples
>>>>>>> + * @return On error a negative value is returned, on success zero or the number
>>>>>>> + * of bytes used to encode the data read from the input buffer.
>>>>>>> + */
>>>>>>> +int avcodec_encode_audio2(AVCodecContext *avctx, uint8_t *buf, int buf_size,
>>>>>>> +                          const AVFrame *frame);
>>>>>> At some point, we should do something about the output buffer
>>>>>> allocation too.  Currently, a ridiculous size is allocated in ffmpeg.c
>>>>>> just to be on the safe side.
>>>>> Agree, and should be easy enough to do. Ditto for video, right?
>>>> that was discussed previously, in short summary yes but noone did it
>>>> Also with encoding into an AVPacket reallocation should be quite easy
>>>> as the pointer is easy changeable
>>> +1 for me on this.  Sometimes even the ridiculous size is not enough,
>>> e.g. FLAC encoding.  The ability to reallocate dynamically if larger
>>> frames are created would make things much simpler.
>>>
>>> I like the overall concept for these changes.  I think it would also get
>>> rid of the frame_size=1 for PCM requirement.
>>
>> I'm not sure to understand what you mean by frame_size=1 PCM
>> requirement. Can you please elaborate ?
>
> See:
>
> documentation for avcodec_encode_audio() where PCM is handled
> differently from other codecs with regard to frame size.
>
> ffmpeg.c:944-1011 where PCM is handled separately from other codecs and
> is detected by AVCodecContext.frame_size == 1.
>
> pcm.c:pcm_encode_init() where avctx->frame_size is set to 1.

Ah, right, thanks for the clarification.

-- 
Baptiste COUDURIER
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