/* * Interface to libgsm for gsm encoding/decoding * Copyright (c) 2005 Alban Bedel <albeu@free.fr> * * 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 libgsm.c * Interface to libgsm for gsm encoding/decoding */ #include "avcodec.h" #include <gsm.h> // gsm.h miss some essential constants #define GSM_BLOCK_SIZE 33 #define GSM_FRAME_SIZE 160 static int libgsm_init(AVCodecContext *avctx) { if (avctx->channels > 1 || avctx->sample_rate != 8000) return -1; avctx->frame_size = GSM_FRAME_SIZE; avctx->block_align = GSM_BLOCK_SIZE; avctx->priv_data = gsm_create(); avctx->coded_frame= avcodec_alloc_frame(); avctx->coded_frame->key_frame= 1; return 0; } static int libgsm_close(AVCodecContext *avctx) { 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 < GSM_BLOCK_SIZE) return 0; gsm_encode(avctx->priv_data,data,frame); return GSM_BLOCK_SIZE; } AVCodec libgsm_encoder = { "gsm", CODEC_TYPE_AUDIO, CODEC_ID_GSM, 0, libgsm_init, libgsm_encode_frame, libgsm_close, }; static int libgsm_decode_frame(AVCodecContext *avctx, void *data, int *data_size, uint8_t *buf, int buf_size) { if(buf_size < GSM_BLOCK_SIZE) return 0; if(gsm_decode(avctx->priv_data,buf,data)) return -1; *data_size = GSM_FRAME_SIZE*2; return GSM_BLOCK_SIZE; } AVCodec libgsm_decoder = { "gsm", CODEC_TYPE_AUDIO, CODEC_ID_GSM, 0, libgsm_init, NULL, libgsm_close, libgsm_decode_frame, };