[FFmpeg-devel] [PATCH] Add ATRAC3+ decoder

[Maxim Polijakowski]

Am 14.10.2013 22:09, schrieb Michael Niedermayer:
> On Mon, Oct 14, 2013 at 08:52:04PM +0200, Maxim Polijakowski wrote:
>>>> +    const uint8_t *buf  = avpkt->data;
>>>> +    int buf_size        = avpkt->size;
>>>> +    ATRAC3PContext *ctx = avctx->priv_data;
>>>> +    AVFrame *frame      = data;
>>>> +    int i, ret, ch_unit_id, ch_block = 0, out_ch_index = 0, channels_to_process;
>>>> +    float **samples_p = (float **)frame->extended_data;
>>>> +
>>>> +    frame->nb_samples = ATRAC3P_FRAME_SAMPLES;
>>>> +    if ((ret = ff_get_buffer(avctx, frame, 0)) < 0) {
>>>> +        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
>>>> +        return ret;
>>>> +    }
>>>> +
>>>> +    init_get_bits(&ctx->gb, buf, buf_size * 8);
>>> if ((ret = init_get_bits8(&ctx->gb, avpkt->data, avpkt->size)) < 0)
>>>      return ret;
>> Done.
>>
>>> [...]
>>>
>>>> +
>>>> +/**
>>>> + *  @file
>>>> + *  DSP functions for ATRAC3+ decoder.
>>>> + */
>>>> +
>>>> +#include <math.h>
>>>> +
>>>> +#include "libavutil/float_dsp.h"
>>>> +#include "avcodec.h"
>>>> +#include "sinewin.h"
>>>> +#include "fft.h"
>>>> +#include "atrac3plus.h"
>>>> +#include "atrac3plus_data.h"
>>>> +
>>>> +#define ATRAC3P_MDCT_SIZE (ATRAC3P_SUBBAND_SAMPLES * 2)
>>>> +
>>>> +static AVFloatDSPContext atrac3p_dsp;
>>> This looks strange and is probably incorrect, it probably should be in
>>> private context.
>>>
>> What is wrong with that?
> Initialization uses a local per instance flag
> (avctx->flags & CODEC_FLAG_BITEXACT)
> thus if there are 2 instances, one with the flag set and one not set
> a single global context could only be corrct for both if the flag
> has no effect and would be unused
> so something in this looks wrong, either it shouldt be global or there
> should be no local flag passed to it.

Will the following code:

avpriv_float_dsp_init(&atrac3p_dsp, CODEC_FLAG_BITEXACT);

work correctly for me?

Unfortunately, the purpose of those avctx->flags is completely opaque to 
me...

Best regards
Maxim