/*
  * Interface to libgsm for gsm encoding/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 encoding/decoding
  */
 

 // The idiosyncrasies of GSM-in-WAV are explained at http://kbs.cs.tu-berlin.de/~jutta/toast.html
 

 #include <gsm/gsm.h>

 #include "avcodec.h"
 #include "gsm.h"

 static av_cold int libgsm_encode_init(AVCodecContext *avctx) {

     if (avctx->channels > 1) {
         av_log(avctx, AV_LOG_ERROR, "Mono required for GSM, got %d channels\n",
                avctx->channels);

         return -1;

     }

     if (avctx->sample_rate != 8000) {
         av_log(avctx, AV_LOG_ERROR, "Sample rate 8000Hz required for GSM, got %dHz\n",
                avctx->sample_rate);
         if (avctx->strict_std_compliance > FF_COMPLIANCE_UNOFFICIAL)
             return -1;
     }
     if (avctx->bit_rate != 13000 /* Official */ &&
         avctx->bit_rate != 13200 /* Very common */ &&
         avctx->bit_rate != 0 /* Unknown; a.o. mov does not set bitrate when decoding */ ) {
         av_log(avctx, AV_LOG_ERROR, "Bitrate 13000bps required for GSM, got %dbps\n",
                avctx->bit_rate);
         if (avctx->strict_std_compliance > FF_COMPLIANCE_UNOFFICIAL)
             return -1;

     }

 
     avctx->priv_data = gsm_create();

     switch(avctx->codec_id) {
     case CODEC_ID_GSM:
         avctx->frame_size = GSM_FRAME_SIZE;
         avctx->block_align = GSM_BLOCK_SIZE;
         break;
     case CODEC_ID_GSM_MS: {
         int one = 1;
         gsm_option(avctx->priv_data, GSM_OPT_WAV49, &one);
         avctx->frame_size = 2*GSM_FRAME_SIZE;
         avctx->block_align = GSM_MS_BLOCK_SIZE;
         }
     }
 

     avctx->coded_frame= avcodec_alloc_frame();
     avctx->coded_frame->key_frame= 1;

     return 0;
 }
 

 static av_cold int libgsm_encode_close(AVCodecContext *avctx) {

     av_freep(&avctx->coded_frame);

     gsm_destroy(avctx->priv_data);
     avctx->priv_data = NULL;
     return 0;
 }
 
 static int libgsm_encode_frame(AVCodecContext *avctx,
                                unsigned char *frame, int buf_size, void *data) {
     // we need a full block

     if(buf_size < avctx->block_align) return 0;
 
     switch(avctx->codec_id) {
     case CODEC_ID_GSM:
         gsm_encode(avctx->priv_data,data,frame);
         break;
     case CODEC_ID_GSM_MS:
         gsm_encode(avctx->priv_data,data,frame);
         gsm_encode(avctx->priv_data,((short*)data)+GSM_FRAME_SIZE,frame+32);
     }
     return avctx->block_align;

 }
 
 

 AVCodec ff_libgsm_encoder = {

     .name           = "libgsm",
     .type           = AVMEDIA_TYPE_AUDIO,
     .id             = CODEC_ID_GSM,

     .init           = libgsm_encode_init,

     .encode         = libgsm_encode_frame,

     .close          = libgsm_encode_close,

     .sample_fmts = (const enum AVSampleFormat[]){AV_SAMPLE_FMT_S16,AV_SAMPLE_FMT_NONE},

     .long_name = NULL_IF_CONFIG_SMALL("libgsm GSM"),

 };
 

 AVCodec ff_libgsm_ms_encoder = {

     .name           = "libgsm_ms",
     .type           = AVMEDIA_TYPE_AUDIO,
     .id             = CODEC_ID_GSM_MS,

     .init           = libgsm_encode_init,

     .encode         = libgsm_encode_frame,

     .close          = libgsm_encode_close,

     .sample_fmts = (const enum AVSampleFormat[]){AV_SAMPLE_FMT_S16,AV_SAMPLE_FMT_NONE},

     .long_name = NULL_IF_CONFIG_SMALL("libgsm GSM Microsoft variant"),

 };
 

 typedef struct LibGSMDecodeContext {
     AVFrame frame;
     struct gsm_state *state;
 } LibGSMDecodeContext;
 

 static av_cold int libgsm_decode_init(AVCodecContext *avctx) {

     LibGSMDecodeContext *s = avctx->priv_data;
 

     if (avctx->channels > 1) {
         av_log(avctx, AV_LOG_ERROR, "Mono required for GSM, got %d channels\n",
                avctx->channels);
         return -1;
     }
 
     if (!avctx->channels)
         avctx->channels = 1;
 
     if (!avctx->sample_rate)
         avctx->sample_rate = 8000;
 
     avctx->sample_fmt = AV_SAMPLE_FMT_S16;
 

     s->state = gsm_create();

 
     switch(avctx->codec_id) {
     case CODEC_ID_GSM:
         avctx->frame_size  = GSM_FRAME_SIZE;
         avctx->block_align = GSM_BLOCK_SIZE;
         break;
     case 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;
         }
     }
 

     avcodec_get_frame_defaults(&s->frame);
     avctx->coded_frame = &s->frame;
 

     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;

     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 */
     s->frame.nb_samples = avctx->frame_size;
     if ((ret = avctx->get_buffer(avctx, &s->frame)) < 0) {
         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
         return ret;
     }
     samples = (int16_t *)s->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;
     *(AVFrame *)data = s->frame;
 

     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 == CODEC_ID_GSM_MS)
         gsm_option(s->state, GSM_OPT_WAV49, &one);

 }
 

 AVCodec ff_libgsm_decoder = {

     .name           = "libgsm",
     .type           = AVMEDIA_TYPE_AUDIO,
     .id             = CODEC_ID_GSM,

     .priv_data_size = sizeof(LibGSMDecodeContext),

     .init           = libgsm_decode_init,
     .close          = libgsm_decode_close,

     .decode         = libgsm_decode_frame,

     .flush          = libgsm_flush,

     .capabilities   = CODEC_CAP_DR1,

     .long_name = NULL_IF_CONFIG_SMALL("libgsm GSM"),

 };

 AVCodec ff_libgsm_ms_decoder = {

     .name           = "libgsm_ms",
     .type           = AVMEDIA_TYPE_AUDIO,
     .id             = 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   = CODEC_CAP_DR1,

     .long_name = NULL_IF_CONFIG_SMALL("libgsm GSM Microsoft variant"),

 };