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libavcodec
libgsmenc.c
Go to the documentation of this file.
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/*
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* Interface to libgsm for GSM encoding
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* Copyright (c) 2005 Alban Bedel <albeu@free.fr>
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* Copyright (c) 2006, 2007 Michel Bardiaux <mbardiaux@mediaxim.be>
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg 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 GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* Interface to libgsm for GSM encoding
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*/
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// The idiosyncrasies of GSM-in-WAV are explained at http://kbs.cs.tu-berlin.de/~jutta/toast.html
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#include "config.h"
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#if HAVE_GSM_H
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#include <
gsm.h
>
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#else
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#include <gsm/gsm.h>
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#endif
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#include "
libavutil/common.h
"
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#include "
avcodec.h
"
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#include "
internal.h
"
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#include "
gsm.h
"
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static
av_cold
int
libgsm_encode_close
(
AVCodecContext
*avctx) {
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gsm_destroy(avctx->
priv_data
);
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avctx->
priv_data
=
NULL
;
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return
0;
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}
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static
av_cold
int
libgsm_encode_init
(
AVCodecContext
*avctx) {
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if
(avctx->
channels
> 1) {
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av_log
(avctx,
AV_LOG_ERROR
,
"Mono required for GSM, got %d channels\n"
,
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avctx->
channels
);
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return
-1;
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}
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if
(avctx->
sample_rate
!= 8000) {
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av_log
(avctx,
AV_LOG_ERROR
,
"Sample rate 8000Hz required for GSM, got %dHz\n"
,
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avctx->
sample_rate
);
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if
(avctx->
strict_std_compliance
>
FF_COMPLIANCE_UNOFFICIAL
)
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return
-1;
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}
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if
(avctx->
bit_rate
!= 13000
/* Official */
&&
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avctx->
bit_rate
!= 13200
/* Very common */
&&
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avctx->
bit_rate
!= 0
/* Unknown; a.o. mov does not set bitrate when decoding */
) {
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av_log
(avctx,
AV_LOG_ERROR
,
"Bitrate 13000bps required for GSM, got %dbps\n"
,
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avctx->
bit_rate
);
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if
(avctx->
strict_std_compliance
>
FF_COMPLIANCE_UNOFFICIAL
)
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return
-1;
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}
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avctx->
priv_data
= gsm_create();
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if
(!avctx->
priv_data
)
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goto
error;
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switch
(avctx->
codec_id
) {
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case
AV_CODEC_ID_GSM
:
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avctx->
frame_size
=
GSM_FRAME_SIZE
;
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avctx->
block_align
=
GSM_BLOCK_SIZE
;
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break
;
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case
AV_CODEC_ID_GSM_MS
: {
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int
one = 1;
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gsm_option(avctx->
priv_data
, GSM_OPT_WAV49, &one);
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avctx->
frame_size
= 2*
GSM_FRAME_SIZE
;
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avctx->
block_align
=
GSM_MS_BLOCK_SIZE
;
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}
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}
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return
0;
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error:
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libgsm_encode_close
(avctx);
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return
-1;
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}
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static
int
libgsm_encode_frame
(
AVCodecContext
*avctx,
AVPacket
*avpkt,
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const
AVFrame
*
frame
,
int
*got_packet_ptr)
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{
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int
ret
;
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gsm_signal *samples = (gsm_signal *)frame->
data
[0];
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struct
gsm_state *
state
= avctx->
priv_data
;
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if
((ret =
ff_alloc_packet2
(avctx, avpkt, avctx->
block_align
)) < 0)
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return
ret;
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switch
(avctx->
codec_id
) {
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case
AV_CODEC_ID_GSM
:
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gsm_encode(
state
, samples, avpkt->
data
);
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break
;
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case
AV_CODEC_ID_GSM_MS
:
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gsm_encode(
state
, samples, avpkt->
data
);
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gsm_encode(
state
, samples +
GSM_FRAME_SIZE
, avpkt->
data
+ 32);
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}
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*got_packet_ptr = 1;
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return
0;
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}
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#if CONFIG_LIBGSM_ENCODER
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AVCodec
ff_libgsm_encoder = {
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.
name
=
"libgsm"
,
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.long_name =
NULL_IF_CONFIG_SMALL
(
"libgsm GSM"
),
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.type =
AVMEDIA_TYPE_AUDIO
,
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.id =
AV_CODEC_ID_GSM
,
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.init =
libgsm_encode_init
,
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.encode2 =
libgsm_encode_frame
,
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.close =
libgsm_encode_close
,
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.sample_fmts = (
const
enum
AVSampleFormat
[]){
AV_SAMPLE_FMT_S16
,
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AV_SAMPLE_FMT_NONE
},
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};
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#endif
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#if CONFIG_LIBGSM_MS_ENCODER
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AVCodec
ff_libgsm_ms_encoder = {
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.
name
=
"libgsm_ms"
,
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.long_name =
NULL_IF_CONFIG_SMALL
(
"libgsm GSM Microsoft variant"
),
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.type =
AVMEDIA_TYPE_AUDIO
,
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.id =
AV_CODEC_ID_GSM_MS
,
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.init =
libgsm_encode_init
,
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.encode2 =
libgsm_encode_frame
,
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.close =
libgsm_encode_close
,
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.sample_fmts = (
const
enum
AVSampleFormat
[]){
AV_SAMPLE_FMT_S16
,
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AV_SAMPLE_FMT_NONE
},
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};
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#endif
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