path: root/libavcodec/mp3_header_decompress_bsf.c (plain)
blob: 22c1ef0220efea64151edee2cc19307fdccdb1ba

1	/*
2	* copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
3	*
4	* This file is part of FFmpeg.
5	*
6	* FFmpeg is free software; you can redistribute it and/or
7	* modify it under the terms of the GNU Lesser General Public
8	* License as published by the Free Software Foundation; either
9	* version 2.1 of the License, or (at your option) any later version.
10	*
11	* FFmpeg is distributed in the hope that it will be useful,
12	* but WITHOUT ANY WARRANTY; without even the implied warranty of
13	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14	* Lesser General Public License for more details.
15	*
16	* You should have received a copy of the GNU Lesser General Public
17	* License along with FFmpeg; if not, write to the Free Software
18	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19	*/
20
21	#include "libavutil/common.h"
22	#include "libavutil/intreadwrite.h"
23	#include "avcodec.h"
24	#include "bsf.h"
25	#include "mpegaudiodecheader.h"
26	#include "mpegaudiodata.h"
27
28
29	static int mp3_header_decompress(AVBSFContext *ctx, AVPacket *out)
30	{
31	AVPacket *in;
32	uint32_t header;
33	int sample_rate= ctx->par_in->sample_rate;
34	int sample_rate_index=0;
35	int lsf, mpeg25, bitrate_index, frame_size, ret;
36	uint8_t *buf;
37	int buf_size;
38
39	ret = ff_bsf_get_packet(ctx, &in);
40	if (ret < 0)
41	return ret;
42
43	buf = in->data;
44	buf_size = in->size;
45
46	header = AV_RB32(buf);
47	if(ff_mpa_check_header(header) >= 0){
48	av_packet_move_ref(out, in);
49	av_packet_free(&in);
50
51	return 0;
52	}
53
54	if(ctx->par_in->extradata_size != 15 || strcmp(ctx->par_in->extradata, "FFCMP3 0.0")){
55	av_log(ctx, AV_LOG_ERROR, "Extradata invalid %d\n", ctx->par_in->extradata_size);
56	ret = AVERROR(EINVAL);
57	goto fail;
58	}
59
60	header= AV_RB32(ctx->par_in->extradata+11) & MP3_MASK;
61
62	lsf = sample_rate < (24000+32000)/2;
63	mpeg25 = sample_rate < (12000+16000)/2;
64	sample_rate_index= (header>>10)&3;
65	sample_rate= avpriv_mpa_freq_tab[sample_rate_index] >> (lsf + mpeg25); //in case sample rate is a little off
66
67	for(bitrate_index=2; bitrate_index<30; bitrate_index++){
68	frame_size = avpriv_mpa_bitrate_tab[lsf][2][bitrate_index>>1];
69	frame_size = (frame_size * 144000) / (sample_rate << lsf) + (bitrate_index&1);
70	if(frame_size == buf_size + 4)
71	break;
72	if(frame_size == buf_size + 6)
73	break;
74	}
75	if(bitrate_index == 30){
76	av_log(ctx, AV_LOG_ERROR, "Could not find bitrate_index.\n");
77	ret = AVERROR(EINVAL);
78	goto fail;
79	}
80
81	header |= (bitrate_index&1)<<9;
82	header |= (bitrate_index>>1)<<12;
83	header |= (frame_size == buf_size + 4)<<16; //FIXME actually set a correct crc instead of 0
84
85	ret = av_new_packet(out, frame_size);
86	if (ret < 0)
87	goto fail;
88	ret = av_packet_copy_props(out, in);
89	if (ret < 0) {
90	av_packet_free(&out);
91	goto fail;
92	}
93	memcpy(out->data + frame_size - buf_size, buf, buf_size + AV_INPUT_BUFFER_PADDING_SIZE);
94
95	if(ctx->par_in->channels==2){
96	uint8_t *p= out->data + frame_size - buf_size;
97	if(lsf){
98	FFSWAP(int, p[1], p[2]);
99	header |= (p[1] & 0xC0)>>2;
100	p[1] &= 0x3F;
101	}else{
102	header |= p[1] & 0x30;
103	p[1] &= 0xCF;
104	}
105	}
106
107	AV_WB32(out->data, header);
108
109	ret = 0;
110
111	fail:
112	av_packet_free(&in);
113	return ret;
114	}
115
116	static const enum AVCodecID codec_ids[] = {
117	AV_CODEC_ID_MP3, AV_CODEC_ID_NONE,
118	};
119
120	const AVBitStreamFilter ff_mp3_header_decompress_bsf = {
121	.name = "mp3decomp",
122	.filter = mp3_header_decompress,
123	.codec_ids = codec_ids,
124	};
125