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ffmpeg / libavcodec / mp3lameaudio.c @ bb71e317

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/*
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 * Interface to libmp3lame for mp3 encoding
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 * Copyright (c) 2002 Lennert Buytenhek <buytenh@gnu.org>
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 *
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 * This program is free software; you can redistribute it and/or modify
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 * it under the terms of the GNU General Public License as published by
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 * the Free Software Foundation; either version 2 of the License, or
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 * (at your option) any later version.
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 *
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 * This program is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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 * GNU General Public License for more details.
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 *
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 * You should have received a copy of the GNU General Public License
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 * along with this program; if not, write to the Free Software
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 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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 */
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#include "avcodec.h"
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#include <math.h>
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#include "mpegaudio.h"
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#include <lame/lame.h>
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typedef struct Mp3AudioContext {
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        lame_global_flags *gfp;
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        int first_frame;
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        int stereo;
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} Mp3AudioContext;
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static int MP3lame_encode_init(AVCodecContext *avctx)
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{
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        Mp3AudioContext *s = avctx->priv_data;
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        if (avctx->channels > 2)
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                return -1;
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        s->first_frame = 1;
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        s->stereo = avctx->channels > 1 ? 1 : 0;
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        if ((s->gfp = lame_init()) == NULL)
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                goto err;
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        lame_set_in_samplerate(s->gfp, avctx->sample_rate);
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        lame_set_out_samplerate(s->gfp, avctx->sample_rate);
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        lame_set_num_channels(s->gfp, avctx->channels);
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        /* lame 3.91 dies on quality != 5 */
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        lame_set_quality(s->gfp, 5);
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        /* lame 3.91 doesn't work in mono */
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        lame_set_mode(s->gfp, JOINT_STEREO);
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        lame_set_brate(s->gfp, avctx->bit_rate/1000);
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        if (lame_init_params(s->gfp) < 0)
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                goto err_close;
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        avctx->frame_size = MPA_FRAME_SIZE;
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        avctx->key_frame = 1;
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        return 0;
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err_close:
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        lame_close(s->gfp);
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err:
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        return -1;
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}
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int MP3lame_encode_frame(AVCodecContext *avctx,
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                     unsigned char *frame, int buf_size, void *data)
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{
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        Mp3AudioContext *s = avctx->priv_data;
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        int num;
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        /* lame 3.91 dies on '1-channel interleaved' data */
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        if (s->stereo) {
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                num = lame_encode_buffer_interleaved(s->gfp, data,
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                        MPA_FRAME_SIZE, frame, buf_size);
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        } else {
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                num = lame_encode_buffer(s->gfp, data, data, MPA_FRAME_SIZE,
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                        frame, buf_size);
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        }
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        /* lame 3.91 outputs the first frame as garbage */
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        if (s->first_frame)
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                s->first_frame = num = 0;
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        return num;
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}
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int MP3lame_encode_close(AVCodecContext *avctx)
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{
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        Mp3AudioContext *s = avctx->priv_data;
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        lame_close(s->gfp);
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        return 0;
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}
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AVCodec mp3lame_encoder = {
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    "mp3",
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    CODEC_TYPE_AUDIO,
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    CODEC_ID_MP3LAME,
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    sizeof(Mp3AudioContext),
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    MP3lame_encode_init,
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    MP3lame_encode_frame,
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    MP3lame_encode_close
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};