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