1/*
2 * SMPTE 302M decoder
3 * Copyright (c) 2008 Laurent Aimar <fenrir@videolan.org>
4 * Copyright (c) 2009 Baptiste Coudurier <baptiste.coudurier@gmail.com>
5 *
6 * This file is part of Libav.
7 *
8 * Libav is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
12 *
13 * Libav is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
16 * Lesser General Public License for more details.
17 *
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with Libav; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 */
22
23#include "libavutil/intreadwrite.h"
24#include "avcodec.h"
25
26#define AES3_HEADER_LEN 4
27
28typedef struct S302MDecodeContext {
29    AVFrame frame;
30} S302MDecodeContext;
31
32static int s302m_parse_frame_header(AVCodecContext *avctx, const uint8_t *buf,
33                                    int buf_size)
34{
35    uint32_t h;
36    int frame_size, channels, bits;
37
38    if (buf_size <= AES3_HEADER_LEN) {
39        av_log(avctx, AV_LOG_ERROR, "frame is too short\n");
40        return AVERROR_INVALIDDATA;
41    }
42
43    /*
44     * AES3 header :
45     * size:            16
46     * number channels   2
47     * channel_id        8
48     * bits per samples  2
49     * alignments        4
50     */
51
52    h = AV_RB32(buf);
53    frame_size =  (h >> 16) & 0xffff;
54    channels   = ((h >> 14) & 0x0003) * 2 +  2;
55    bits       = ((h >>  4) & 0x0003) * 4 + 16;
56
57    if (AES3_HEADER_LEN + frame_size != buf_size || bits > 24) {
58        av_log(avctx, AV_LOG_ERROR, "frame has invalid header\n");
59        return AVERROR_INVALIDDATA;
60    }
61
62    /* Set output properties */
63    avctx->bits_per_coded_sample = bits;
64    if (bits > 16)
65        avctx->sample_fmt = AV_SAMPLE_FMT_S32;
66    else
67        avctx->sample_fmt = AV_SAMPLE_FMT_S16;
68
69    avctx->channels    = channels;
70    avctx->sample_rate = 48000;
71    avctx->bit_rate    = 48000 * avctx->channels * (avctx->bits_per_coded_sample + 4) +
72                         32 * (48000 / (buf_size * 8 /
73                                        (avctx->channels *
74                                         (avctx->bits_per_coded_sample + 4))));
75
76    return frame_size;
77}
78
79static int s302m_decode_frame(AVCodecContext *avctx, void *data,
80                              int *got_frame_ptr, AVPacket *avpkt)
81{
82    S302MDecodeContext *s = avctx->priv_data;
83    const uint8_t *buf = avpkt->data;
84    int buf_size       = avpkt->size;
85    int block_size, ret;
86
87    int frame_size = s302m_parse_frame_header(avctx, buf, buf_size);
88    if (frame_size < 0)
89        return frame_size;
90
91    buf_size -= AES3_HEADER_LEN;
92    buf      += AES3_HEADER_LEN;
93
94    /* get output buffer */
95    block_size = (avctx->bits_per_coded_sample + 4) / 4;
96    s->frame.nb_samples = 2 * (buf_size / block_size) / avctx->channels;
97    if ((ret = avctx->get_buffer(avctx, &s->frame)) < 0) {
98        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
99        return ret;
100    }
101
102    buf_size = (s->frame.nb_samples * avctx->channels / 2) * block_size;
103
104    if (avctx->bits_per_coded_sample == 24) {
105        uint32_t *o = (uint32_t *)s->frame.data[0];
106        for (; buf_size > 6; buf_size -= 7) {
107            *o++ = (av_reverse[buf[2]]        << 24) |
108                   (av_reverse[buf[1]]        << 16) |
109                   (av_reverse[buf[0]]        <<  8);
110            *o++ = (av_reverse[buf[6] & 0xf0] << 28) |
111                   (av_reverse[buf[5]]        << 20) |
112                   (av_reverse[buf[4]]        << 12) |
113                   (av_reverse[buf[3] & 0x0f] <<  4);
114            buf += 7;
115        }
116    } else if (avctx->bits_per_coded_sample == 20) {
117        uint32_t *o = (uint32_t *)s->frame.data[0];
118        for (; buf_size > 5; buf_size -= 6) {
119            *o++ = (av_reverse[buf[2] & 0xf0] << 28) |
120                   (av_reverse[buf[1]]        << 20) |
121                   (av_reverse[buf[0]]        << 12);
122            *o++ = (av_reverse[buf[5] & 0xf0] << 28) |
123                   (av_reverse[buf[4]]        << 20) |
124                   (av_reverse[buf[3]]        << 12);
125            buf += 6;
126        }
127    } else {
128        uint16_t *o = (uint16_t *)s->frame.data[0];
129        for (; buf_size > 4; buf_size -= 5) {
130            *o++ = (av_reverse[buf[1]]        <<  8) |
131                    av_reverse[buf[0]];
132            *o++ = (av_reverse[buf[4] & 0xf0] << 12) |
133                   (av_reverse[buf[3]]        <<  4) |
134                   (av_reverse[buf[2]]        >>  4);
135            buf += 5;
136        }
137    }
138
139    *got_frame_ptr   = 1;
140    *(AVFrame *)data = s->frame;
141
142    return avpkt->size;
143}
144
145static int s302m_decode_init(AVCodecContext *avctx)
146{
147    S302MDecodeContext *s = avctx->priv_data;
148
149    avcodec_get_frame_defaults(&s->frame);
150    avctx->coded_frame = &s->frame;
151
152    return 0;
153}
154
155
156AVCodec ff_s302m_decoder = {
157    .name           = "s302m",
158    .type           = AVMEDIA_TYPE_AUDIO,
159    .id             = CODEC_ID_S302M,
160    .priv_data_size = sizeof(S302MDecodeContext),
161    .init           = s302m_decode_init,
162    .decode         = s302m_decode_frame,
163    .capabilities   = CODEC_CAP_DR1,
164    .long_name      = NULL_IF_CONFIG_SMALL("SMPTE 302M"),
165};
166