/*
  * Interface to libgsm for GSM decoding
  * Copyright (c) 2005 Alban Bedel <albeu@free.fr>
  * Copyright (c) 2006, 2007 Michel Bardiaux <mbardiaux@mediaxim.be>
  *

  * 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
  */
 
 /**
  * @file
  * Interface to libgsm for GSM decoding
  */
 
 // The idiosyncrasies of GSM-in-WAV are explained at http://kbs.cs.tu-berlin.de/~jutta/toast.html
 
 #include "config.h"
 #if HAVE_GSM_H
 #include <gsm.h>
 #else
 #include <gsm/gsm.h>
 #endif
 
 #include "libavutil/channel_layout.h"
 #include "libavutil/common.h"
 
 #include "avcodec.h"
 #include "internal.h"
 #include "gsm.h"
 
 typedef struct LibGSMDecodeContext {
     struct gsm_state *state;
 } LibGSMDecodeContext;
 
 static av_cold int libgsm_decode_init(AVCodecContext *avctx) {
     LibGSMDecodeContext *s = avctx->priv_data;
 
     avctx->channels       = 1;
     avctx->channel_layout = AV_CH_LAYOUT_MONO;

     if (!avctx->sample_rate)
         avctx->sample_rate = 8000;

     avctx->sample_fmt     = AV_SAMPLE_FMT_S16;
 
     s->state = gsm_create();
 
     switch(avctx->codec_id) {
     case AV_CODEC_ID_GSM:
         avctx->frame_size  = GSM_FRAME_SIZE;
         avctx->block_align = GSM_BLOCK_SIZE;
         break;
     case AV_CODEC_ID_GSM_MS: {
         int one = 1;
         gsm_option(s->state, GSM_OPT_WAV49, &one);
         avctx->frame_size  = 2 * GSM_FRAME_SIZE;
         avctx->block_align = GSM_MS_BLOCK_SIZE;
         }
     }
 
     return 0;
 }
 
 static av_cold int libgsm_decode_close(AVCodecContext *avctx) {
     LibGSMDecodeContext *s = avctx->priv_data;
 
     gsm_destroy(s->state);
     s->state = NULL;
     return 0;
 }
 
 static int libgsm_decode_frame(AVCodecContext *avctx, void *data,
                                int *got_frame_ptr, AVPacket *avpkt)
 {
     int i, ret;
     LibGSMDecodeContext *s = avctx->priv_data;
     AVFrame *frame         = data;
     uint8_t *buf = avpkt->data;
     int buf_size = avpkt->size;
     int16_t *samples;
 
     if (buf_size < avctx->block_align) {
         av_log(avctx, AV_LOG_ERROR, "Packet is too small\n");
         return AVERROR_INVALIDDATA;
     }
 
     /* get output buffer */
     frame->nb_samples = avctx->frame_size;

     if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)

         return ret;
     samples = (int16_t *)frame->data[0];
 
     for (i = 0; i < avctx->frame_size / GSM_FRAME_SIZE; i++) {
         if ((ret = gsm_decode(s->state, buf, samples)) < 0)
             return -1;
         buf     += GSM_BLOCK_SIZE;
         samples += GSM_FRAME_SIZE;
     }
 
     *got_frame_ptr = 1;
 
     return avctx->block_align;
 }
 
 static void libgsm_flush(AVCodecContext *avctx) {
     LibGSMDecodeContext *s = avctx->priv_data;
     int one = 1;
 
     gsm_destroy(s->state);
     s->state = gsm_create();
     if (avctx->codec_id == AV_CODEC_ID_GSM_MS)
         gsm_option(s->state, GSM_OPT_WAV49, &one);
 }
 

 #if CONFIG_LIBGSM_DECODER

 AVCodec ff_libgsm_decoder = {
     .name           = "libgsm",
     .long_name      = NULL_IF_CONFIG_SMALL("libgsm GSM"),
     .type           = AVMEDIA_TYPE_AUDIO,
     .id             = AV_CODEC_ID_GSM,
     .priv_data_size = sizeof(LibGSMDecodeContext),
     .init           = libgsm_decode_init,
     .close          = libgsm_decode_close,
     .decode         = libgsm_decode_frame,
     .flush          = libgsm_flush,

     .capabilities   = AV_CODEC_CAP_DR1,

 };

 #endif
 #if CONFIG_LIBGSM_MS_DECODER

 AVCodec ff_libgsm_ms_decoder = {
     .name           = "libgsm_ms",
     .long_name      = NULL_IF_CONFIG_SMALL("libgsm GSM Microsoft variant"),
     .type           = AVMEDIA_TYPE_AUDIO,
     .id             = AV_CODEC_ID_GSM_MS,
     .priv_data_size = sizeof(LibGSMDecodeContext),
     .init           = libgsm_decode_init,
     .close          = libgsm_decode_close,
     .decode         = libgsm_decode_frame,
     .flush          = libgsm_flush,

     .capabilities   = AV_CODEC_CAP_DR1,

 };

 #endif