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  1. /*
  2.  * Interface to libgsm for GSM encoding
  3.  * Copyright (c) 2005 Alban Bedel <albeu@free.fr>
  4.  * Copyright (c) 2006, 2007 Michel Bardiaux <mbardiaux@mediaxim.be>
  5.  *
  6.  * This file is part of FFmpeg.
  7.  *
  8.  * FFmpeg is free software; you can redistribute it and/or
  9.  * modify it under the terms of the GNU Lesser General Public
  10.  * License as published by the Free Software Foundation; either
  11.  * version 2.1 of the License, or (at your option) any later version.
  12.  *
  13.  * FFmpeg is distributed in the hope that it will be useful,
  14.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16.  * Lesser General Public License for more details.
  17.  *
  18.  * You should have received a copy of the GNU Lesser General Public
  19.  * License along with FFmpeg; if not, write to the Free Software
  20.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21.  */
  22.  
  23. /**
  24.  * @file
  25.  * Interface to libgsm for GSM encoding
  26.  */
  27.  
  28. // The idiosyncrasies of GSM-in-WAV are explained at http://kbs.cs.tu-berlin.de/~jutta/toast.html
  29.  
  30. #include "config.h"
  31. #if HAVE_GSM_H
  32. #include <gsm.h>
  33. #else
  34. #include <gsm/gsm.h>
  35. #endif
  36.  
  37. #include "libavutil/common.h"
  38.  
  39. #include "avcodec.h"
  40. #include "internal.h"
  41. #include "gsm.h"
  42.  
  43. static av_cold int libgsm_encode_close(AVCodecContext *avctx) {
  44.     gsm_destroy(avctx->priv_data);
  45.     avctx->priv_data = NULL;
  46.     return 0;
  47. }
  48.  
  49. static av_cold int libgsm_encode_init(AVCodecContext *avctx) {
  50.     if (avctx->channels > 1) {
  51.         av_log(avctx, AV_LOG_ERROR, "Mono required for GSM, got %d channels\n",
  52.                avctx->channels);
  53.         return -1;
  54.     }
  55.  
  56.     if (avctx->sample_rate != 8000) {
  57.         av_log(avctx, AV_LOG_ERROR, "Sample rate 8000Hz required for GSM, got %dHz\n",
  58.                avctx->sample_rate);
  59.         if (avctx->strict_std_compliance > FF_COMPLIANCE_UNOFFICIAL)
  60.             return -1;
  61.     }
  62.     if (avctx->bit_rate != 13000 /* Official */ &&
  63.         avctx->bit_rate != 13200 /* Very common */ &&
  64.         avctx->bit_rate != 0 /* Unknown; a.o. mov does not set bitrate when decoding */ ) {
  65.         av_log(avctx, AV_LOG_ERROR, "Bitrate 13000bps required for GSM, got %dbps\n",
  66.                avctx->bit_rate);
  67.         if (avctx->strict_std_compliance > FF_COMPLIANCE_UNOFFICIAL)
  68.             return -1;
  69.     }
  70.  
  71.     avctx->priv_data = gsm_create();
  72.     if (!avctx->priv_data)
  73.         goto error;
  74.  
  75.     switch(avctx->codec_id) {
  76.     case AV_CODEC_ID_GSM:
  77.         avctx->frame_size = GSM_FRAME_SIZE;
  78.         avctx->block_align = GSM_BLOCK_SIZE;
  79.         break;
  80.     case AV_CODEC_ID_GSM_MS: {
  81.         int one = 1;
  82.         gsm_option(avctx->priv_data, GSM_OPT_WAV49, &one);
  83.         avctx->frame_size = 2*GSM_FRAME_SIZE;
  84.         avctx->block_align = GSM_MS_BLOCK_SIZE;
  85.         }
  86.     }
  87.  
  88.     return 0;
  89. error:
  90.     libgsm_encode_close(avctx);
  91.     return -1;
  92. }
  93.  
  94. static int libgsm_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
  95.                                const AVFrame *frame, int *got_packet_ptr)
  96. {
  97.     int ret;
  98.     gsm_signal *samples = (gsm_signal *)frame->data[0];
  99.     struct gsm_state *state = avctx->priv_data;
  100.  
  101.     if ((ret = ff_alloc_packet2(avctx, avpkt, avctx->block_align, 0)) < 0)
  102.         return ret;
  103.  
  104.     switch(avctx->codec_id) {
  105.     case AV_CODEC_ID_GSM:
  106.         gsm_encode(state, samples, avpkt->data);
  107.         break;
  108.     case AV_CODEC_ID_GSM_MS:
  109.         gsm_encode(state, samples,                  avpkt->data);
  110.         gsm_encode(state, samples + GSM_FRAME_SIZE, avpkt->data + 32);
  111.     }
  112.  
  113.     *got_packet_ptr = 1;
  114.     return 0;
  115. }
  116.  
  117.  
  118. #if CONFIG_LIBGSM_ENCODER
  119. AVCodec ff_libgsm_encoder = {
  120.     .name           = "libgsm",
  121.     .long_name      = NULL_IF_CONFIG_SMALL("libgsm GSM"),
  122.     .type           = AVMEDIA_TYPE_AUDIO,
  123.     .id             = AV_CODEC_ID_GSM,
  124.     .init           = libgsm_encode_init,
  125.     .encode2        = libgsm_encode_frame,
  126.     .close          = libgsm_encode_close,
  127.     .sample_fmts    = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16,
  128.                                                      AV_SAMPLE_FMT_NONE },
  129. };
  130. #endif
  131. #if CONFIG_LIBGSM_MS_ENCODER
  132. AVCodec ff_libgsm_ms_encoder = {
  133.     .name           = "libgsm_ms",
  134.     .long_name      = NULL_IF_CONFIG_SMALL("libgsm GSM Microsoft variant"),
  135.     .type           = AVMEDIA_TYPE_AUDIO,
  136.     .id             = AV_CODEC_ID_GSM_MS,
  137.     .init           = libgsm_encode_init,
  138.     .encode2        = libgsm_encode_frame,
  139.     .close          = libgsm_encode_close,
  140.     .sample_fmts    = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16,
  141.                                                      AV_SAMPLE_FMT_NONE },
  142. };
  143. #endif
  144.