FFmpeg/libavcodec/libspeexdec.c

/*
 * Copyright (C) 2008 David Conrad
 *
 * This file is part of Libav.
 *
 * Libav 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.
 *
 * Libav 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 Libav; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <speex/speex.h>
#include <speex/speex_header.h>
#include <speex/speex_stereo.h>
#include <speex/speex_callbacks.h>
#include "avcodec.h"

typedef struct {
    SpeexBits bits;
    SpeexStereoState stereo;
    void *dec_state;
    SpeexHeader *header;
    int frame_size;
} LibSpeexContext;


static av_cold int libspeex_decode_init(AVCodecContext *avctx)
{
    LibSpeexContext *s = avctx->priv_data;
    const SpeexMode *mode;

    // defaults in the case of a missing header
    if (avctx->sample_rate <= 8000)
        mode = &speex_nb_mode;
    else if (avctx->sample_rate <= 16000)
        mode = &speex_wb_mode;
    else
        mode = &speex_uwb_mode;

    if (avctx->extradata_size >= 80)
        s->header = speex_packet_to_header(avctx->extradata, avctx->extradata_size);

    avctx->sample_fmt = AV_SAMPLE_FMT_S16;
    if (s->header) {
        avctx->sample_rate = s->header->rate;
        avctx->channels    = s->header->nb_channels;
        avctx->frame_size  = s->frame_size = s->header->frame_size;
        if (s->header->frames_per_packet)
            avctx->frame_size *= s->header->frames_per_packet;

        mode = speex_lib_get_mode(s->header->mode);
        if (!mode) {
            av_log(avctx, AV_LOG_ERROR, "Unknown Speex mode %d", s->header->mode);
            return AVERROR_INVALIDDATA;
        }
    } else
        av_log(avctx, AV_LOG_INFO, "Missing Speex header, assuming defaults.\n");

    if (avctx->channels > 2) {
        av_log(avctx, AV_LOG_ERROR, "Only stereo and mono are supported.\n");
        return AVERROR(EINVAL);
    }

    speex_bits_init(&s->bits);
    s->dec_state = speex_decoder_init(mode);
    if (!s->dec_state) {
        av_log(avctx, AV_LOG_ERROR, "Error initializing libspeex decoder.\n");
        return -1;
    }

    if (!s->header) {
        speex_decoder_ctl(s->dec_state, SPEEX_GET_FRAME_SIZE, &s->frame_size);
    }

    if (avctx->channels == 2) {
        SpeexCallback callback;
        callback.callback_id = SPEEX_INBAND_STEREO;
        callback.func = speex_std_stereo_request_handler;
        callback.data = &s->stereo;
        s->stereo = (SpeexStereoState)SPEEX_STEREO_STATE_INIT;
        speex_decoder_ctl(s->dec_state, SPEEX_SET_HANDLER, &callback);
    }
    return 0;
}

static int libspeex_decode_frame(AVCodecContext *avctx,
                                 void *data, int *data_size,
                                 AVPacket *avpkt)
{
    uint8_t *buf = avpkt->data;
    int buf_size = avpkt->size;
    LibSpeexContext *s = avctx->priv_data;
    int16_t *output = data;
    int out_size, ret, consumed = 0;

    /* check output buffer size */
    out_size = s->frame_size * avctx->channels *
               av_get_bytes_per_sample(avctx->sample_fmt);
    if (*data_size < out_size) {
        av_log(avctx, AV_LOG_ERROR, "Output buffer is too small\n");
        return AVERROR(EINVAL);
    }

    /* if there is not enough data left for the smallest possible frame,
       reset the libspeex buffer using the current packet, otherwise ignore
       the current packet and keep decoding frames from the libspeex buffer. */
    if (speex_bits_remaining(&s->bits) < 43) {
        /* check for flush packet */
        if (!buf || !buf_size) {
            *data_size = 0;
            return buf_size;
        }
        /* set new buffer */
        speex_bits_read_from(&s->bits, buf, buf_size);
        consumed = buf_size;
    }

    /* decode a single frame */
    ret = speex_decode_int(s->dec_state, &s->bits, output);
    if (ret <= -2) {
        av_log(avctx, AV_LOG_ERROR, "Error decoding Speex frame.\n");
        return AVERROR_INVALIDDATA;
    }
    if (avctx->channels == 2)
        speex_decode_stereo_int(output, s->frame_size, &s->stereo);

    *data_size = out_size;
    return consumed;
}

static av_cold int libspeex_decode_close(AVCodecContext *avctx)
{
    LibSpeexContext *s = avctx->priv_data;

    speex_header_free(s->header);
    speex_bits_destroy(&s->bits);
    speex_decoder_destroy(s->dec_state);

    return 0;
}

static av_cold void libspeex_decode_flush(AVCodecContext *avctx)
{
    LibSpeexContext *s = avctx->priv_data;
    speex_bits_reset(&s->bits);
}

AVCodec ff_libspeex_decoder = {
    .name           = "libspeex",
    .type           = AVMEDIA_TYPE_AUDIO,
    .id             = CODEC_ID_SPEEX,
    .priv_data_size = sizeof(LibSpeexContext),
    .init           = libspeex_decode_init,
    .close          = libspeex_decode_close,
    .decode         = libspeex_decode_frame,
    .flush          = libspeex_decode_flush,
    .capabilities   = CODEC_CAP_SUBFRAMES | CODEC_CAP_DELAY,
    .long_name = NULL_IF_CONFIG_SMALL("libspeex Speex"),
};