On Tue, Mar 24, 2015 at 7:35 AM, Anton Khirnov <[email protected]> wrote:
> Quoting Hendrik Leppkes (2015-03-23 12:45:19)
>> diff --git a/libavcodec/libdcadec.c b/libavcodec/libdcadec.c
>> new file mode 100644
>> index 0000000..7ca8942
>> --- /dev/null
>> +++ b/libavcodec/libdcadec.c
>> @@ -0,0 +1,197 @@
>> +/*
>> + * libdcadec decoder wrapper
>> + * Copyright (C) 2015 Hendrik Leppkes
>> + *
>> + * This file is part of FFmpeg.
>> + *
>> + * FFmpeg is free software; you can redistribute it and/or
>> + * modify it under the terms of the GNU Lesser General Public
>> + * License as published by the Free Software Foundation; either
>> + * version 2.1 of the License, or (at your option) any later version.
>> + *
>> + * FFmpeg is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
>> + * Lesser General Public License for more details.
>> + *
>> + * You should have received a copy of the GNU Lesser General Public
>> + * License along with FFmpeg; if not, write to the Free Software
>> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301
>> USA
>> + */
>> +
>> +#include <libdcadec/dca_context.h>
>> +
>> +#include "libavutil/avassert.h"
>> +#include "libavutil/channel_layout.h"
>> +#include "libavutil/common.h"
>> +#include "libavutil/opt.h"
>> +#include "avcodec.h"
>> +#include "dca.h"
>> +#include "dca_syncwords.h"
>> +#include "internal.h"
>> +
>> +typedef struct DCADecContext {
>> + struct dcadec_context *ctx;
>> + uint8_t *buffer;
>> + int buffer_size;
>> +} DCADecContext;
>> +
>> +static int dcadec_decode_frame(AVCodecContext *avctx, void *data,
>> + int *got_frame_ptr, AVPacket *avpkt)
>> +{
>> + DCADecContext *s = avctx->priv_data;
>> + AVFrame *frame = data;
>> + int ret, i, k;
>> + int **samples, nsamples, channel_mask, sample_rate, bits_per_sample,
>> profile;
>> + uint32_t mrk;
>> + uint8_t *input = avpkt->data;
>> + int input_size = avpkt->size;
>> +
>> + /* convert bytestream syntax to RAW BE format if required */
>> + mrk = AV_RB32(input);
>
> This read should be checked. The packet size can be anything positive.
As far as I know, decoders can rely on input packets being padded to
at least FF_INPUT_BUFFER_PADDING_SIZE, so this read is safe.
Other decoders do the same thing, ie. the native dca decoder. :p
>> + } else
>> + avctx->bit_rate = 0;
>> +
>> + frame->nb_samples = nsamples;
>> + if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
>> + return ret;
>> +
>> + for (i = 0; i < avctx->channels; i++) {
>> + if (frame->format == AV_SAMPLE_FMT_S16P) {
>> + int16_t *plane = (int16_t *)frame->extended_data[i];
>> + for (k = 0; k < nsamples; k++)
>> + plane[k] = samples[i][k];
>> + } else {
>> + int32_t *plane = (int32_t *)frame->extended_data[i];
>> + int shift = 32 - bits_per_sample;
>> + for (k = 0; k < nsamples; k++)
>> + plane[k] = samples[i][k] << shift;
>> + }
>> + }
>
> This looks awfully inefficient, but I guess nobody cares.
>
There doesn't seem to be a DSP function that does such a conversion,
so generic C it was.
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