text: /*
   * 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 "internal.h"
  #include "gsm.h"
  
  static av_cold int libgsm_encode_close(AVCodecContext *avctx) {
  #if FF_API_OLD_ENCODE_AUDIO
      av_freep(&avctx->coded_frame);
  #endif
      gsm_destroy(avctx->priv_data);
      avctx->priv_data = NULL;
      return 0;
  }
  
  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();
      if (!avctx->priv_data)
          goto error;
  
      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;
          }
      }
  
  #if FF_API_OLD_ENCODE_AUDIO
      avctx->coded_frame= avcodec_alloc_frame();
      if (!avctx->coded_frame)
          goto error;
  #endif
  
      return 0;
  error:
      libgsm_encode_close(avctx);
      return -1;
  }
  
  static int libgsm_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
                                 const AVFrame *frame, int *got_packet_ptr)
  {
      int ret;
      gsm_signal *samples = (gsm_signal *)frame->data[0];
      struct gsm_state *state = avctx->priv_data;
  
      if ((ret = ff_alloc_packet2(avctx, avpkt, avctx->block_align)))
          return ret;
  
      switch(avctx->codec_id) {
      case CODEC_ID_GSM:
          gsm_encode(state, samples, avpkt->data);
          break;
      case CODEC_ID_GSM_MS:
          gsm_encode(state, samples,                  avpkt->data);
          gsm_encode(state, samples + GSM_FRAME_SIZE, avpkt->data + 32);
      }
  
      *got_packet_ptr = 1;
      return 0;
  }
  
  
  AVCodec ff_libgsm_encoder = {
      .name           = "libgsm",
      .type           = AVMEDIA_TYPE_AUDIO,
      .id             = CODEC_ID_GSM,
      .init           = libgsm_encode_init,
      .encode2        = 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,
      .encode2        = 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"),
  };
  