FFmpeg: libavcodec/gsmdec.c Source File

00001 /*
00002  * gsm 06.10 decoder
00003  * Copyright (c) 2010 Reimar Döffinger <Reimar.Doeffinger@gmx.de>
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg 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  * FFmpeg 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 FFmpeg; 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     avctx->channels = 1;
00036     if (!avctx->sample_rate)
00037         avctx->sample_rate = 8000;
00038     avctx->sample_fmt = AV_SAMPLE_FMT_S16;
00039 
00040     switch (avctx->codec_id) {
00041     case CODEC_ID_GSM:
00042         avctx->frame_size  = GSM_FRAME_SIZE;
00043         avctx->block_align = GSM_BLOCK_SIZE;
00044         break;
00045     case CODEC_ID_GSM_MS:
00046         avctx->frame_size  = 2 * GSM_FRAME_SIZE;
00047         avctx->block_align = GSM_MS_BLOCK_SIZE;
00048     }
00049 
00050     return 0;
00051 }
00052 
00053 static int gsm_decode_frame(AVCodecContext *avctx, void *data,
00054                             int *data_size, AVPacket *avpkt)
00055 {
00056     int res;
00057     GetBitContext gb;
00058     const uint8_t *buf = avpkt->data;
00059     int buf_size = avpkt->size;
00060     int16_t *samples = data;
00061     int frame_bytes = 2 * avctx->frame_size;
00062 
00063     if (*data_size < frame_bytes)
00064         return -1;
00065     *data_size = 0;
00066     if(buf_size < avctx->block_align)
00067         return AVERROR_INVALIDDATA;
00068 
00069     switch (avctx->codec_id) {
00070     case CODEC_ID_GSM:
00071         init_get_bits(&gb, buf, buf_size * 8);
00072         if (get_bits(&gb, 4) != 0xd)
00073             av_log(avctx, AV_LOG_WARNING, "Missing GSM magic!\n");
00074         res = gsm_decode_block(avctx, samples, &gb);
00075         if (res < 0)
00076             return res;
00077         break;
00078     case CODEC_ID_GSM_MS:
00079         res = ff_msgsm_decode_block(avctx, samples, buf);
00080         if (res < 0)
00081             return res;
00082     }
00083     *data_size = frame_bytes;
00084     return avctx->block_align;
00085 }
00086 
00087 AVCodec ff_gsm_decoder = {
00088     "gsm",
00089     AVMEDIA_TYPE_AUDIO,
00090     CODEC_ID_GSM,
00091     sizeof(GSMContext),
00092     gsm_init,
00093     NULL,
00094     NULL,
00095     gsm_decode_frame,
00096     .long_name = NULL_IF_CONFIG_SMALL("GSM"),
00097 };
00098 
00099 AVCodec ff_gsm_ms_decoder = {
00100     "gsm_ms",
00101     AVMEDIA_TYPE_AUDIO,
00102     CODEC_ID_GSM_MS,
00103     sizeof(GSMContext),
00104     gsm_init,
00105     NULL,
00106     NULL,
00107     gsm_decode_frame,
00108     .long_name = NULL_IF_CONFIG_SMALL("GSM Microsoft variant"),
00109 };