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libavcodec/gsmdec.c

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00001 /*
00002  * gsm 06.10 decoder
00003  * Copyright (c) 2010 Reimar Döffinger <Reimar.Doeffinger@gmx.de>
00004  *
00005  * This file is part of Libav.
00006  *
00007  * Libav is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * Libav is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with Libav; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00027 #include "avcodec.h"
00028 #include "get_bits.h"
00029 #include "msgsmdec.h"
00030 
00031 #include "gsmdec_template.c"
00032 
00033 static av_cold int gsm_init(AVCodecContext *avctx)
00034 {
00035     GSMContext *s = avctx->priv_data;
00036 
00037     avctx->channels = 1;
00038     if (!avctx->sample_rate)
00039         avctx->sample_rate = 8000;
00040     avctx->sample_fmt = AV_SAMPLE_FMT_S16;
00041 
00042     switch (avctx->codec_id) {
00043     case CODEC_ID_GSM:
00044         avctx->frame_size  = GSM_FRAME_SIZE;
00045         avctx->block_align = GSM_BLOCK_SIZE;
00046         break;
00047     case CODEC_ID_GSM_MS:
00048         avctx->frame_size  = 2 * GSM_FRAME_SIZE;
00049         avctx->block_align = GSM_MS_BLOCK_SIZE;
00050     }
00051 
00052     avcodec_get_frame_defaults(&s->frame);
00053     avctx->coded_frame = &s->frame;
00054 
00055     return 0;
00056 }
00057 
00058 static int gsm_decode_frame(AVCodecContext *avctx, void *data,
00059                             int *got_frame_ptr, AVPacket *avpkt)
00060 {
00061     GSMContext *s = avctx->priv_data;
00062     int res;
00063     GetBitContext gb;
00064     const uint8_t *buf = avpkt->data;
00065     int buf_size = avpkt->size;
00066     int16_t *samples;
00067 
00068     if (buf_size < avctx->block_align) {
00069         av_log(avctx, AV_LOG_ERROR, "Packet is too small\n");
00070         return AVERROR_INVALIDDATA;
00071     }
00072 
00073     /* get output buffer */
00074     s->frame.nb_samples = avctx->frame_size;
00075     if ((res = avctx->get_buffer(avctx, &s->frame)) < 0) {
00076         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
00077         return res;
00078     }
00079     samples = (int16_t *)s->frame.data[0];
00080 
00081     switch (avctx->codec_id) {
00082     case CODEC_ID_GSM:
00083         init_get_bits(&gb, buf, buf_size * 8);
00084         if (get_bits(&gb, 4) != 0xd)
00085             av_log(avctx, AV_LOG_WARNING, "Missing GSM magic!\n");
00086         res = gsm_decode_block(avctx, samples, &gb);
00087         if (res < 0)
00088             return res;
00089         break;
00090     case CODEC_ID_GSM_MS:
00091         res = ff_msgsm_decode_block(avctx, samples, buf);
00092         if (res < 0)
00093             return res;
00094     }
00095 
00096     *got_frame_ptr   = 1;
00097     *(AVFrame *)data = s->frame;
00098 
00099     return avctx->block_align;
00100 }
00101 
00102 static void gsm_flush(AVCodecContext *avctx)
00103 {
00104     GSMContext *s = avctx->priv_data;
00105     memset(s, 0, sizeof(*s));
00106 }
00107 
00108 AVCodec ff_gsm_decoder = {
00109     .name           = "gsm",
00110     .type           = AVMEDIA_TYPE_AUDIO,
00111     .id             = CODEC_ID_GSM,
00112     .priv_data_size = sizeof(GSMContext),
00113     .init           = gsm_init,
00114     .decode         = gsm_decode_frame,
00115     .flush          = gsm_flush,
00116     .capabilities   = CODEC_CAP_DR1,
00117     .long_name = NULL_IF_CONFIG_SMALL("GSM"),
00118 };
00119 
00120 AVCodec ff_gsm_ms_decoder = {
00121     .name           = "gsm_ms",
00122     .type           = AVMEDIA_TYPE_AUDIO,
00123     .id             = CODEC_ID_GSM_MS,
00124     .priv_data_size = sizeof(GSMContext),
00125     .init           = gsm_init,
00126     .decode         = gsm_decode_frame,
00127     .flush          = gsm_flush,
00128     .capabilities   = CODEC_CAP_DR1,
00129     .long_name = NULL_IF_CONFIG_SMALL("GSM Microsoft variant"),
00130 };
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