* Audio Decoder
*/
+#define BLOCK_TYPE_AUDIO 1
+#define BLOCK_TYPE_INITIAL 2
+#define BLOCK_TYPE_SILENCE 3
+
typedef struct VmdAudioContext {
AVCodecContext *avctx;
- int channels;
- int bits;
- int block_align;
+ int out_bps;
int predictors[2];
} VmdAudioContext;
VmdAudioContext *s = avctx->priv_data;
s->avctx = avctx;
- s->channels = avctx->channels;
- s->bits = avctx->bits_per_coded_sample;
- s->block_align = avctx->block_align;
- avctx->sample_fmt = AV_SAMPLE_FMT_S16;
+ if (avctx->bits_per_coded_sample == 16)
+ avctx->sample_fmt = AV_SAMPLE_FMT_S16;
+ else
+ avctx->sample_fmt = AV_SAMPLE_FMT_U8;
+ s->out_bps = av_get_bits_per_sample_fmt(avctx->sample_fmt) >> 3;
- av_log(s->avctx, AV_LOG_DEBUG, "%d channels, %d bits/sample, block align = %d, sample rate = %d\n",
- s->channels, s->bits, s->block_align, avctx->sample_rate);
+ av_log(avctx, AV_LOG_DEBUG, "%d channels, %d bits/sample, "
+ "block align = %d, sample rate = %d\n",
+ avctx->channels, avctx->bits_per_coded_sample, avctx->block_align,
+ avctx->sample_rate);
return 0;
}
}
static int vmdaudio_loadsound(VmdAudioContext *s, unsigned char *data,
- const uint8_t *buf, int silence, int data_size)
+ const uint8_t *buf, int silent_chunks, int data_size)
{
- int i;
-
-// if (silence)
-// av_log(s->avctx, AV_LOG_INFO, "silent block!\n");
+ int silent_size = s->avctx->block_align * silent_chunks * s->out_bps;
- if (silence) {
- memset(data, 0, data_size * 2);
- } else {
- if (s->bits == 16)
- vmdaudio_decode_audio(s, data, buf, data_size, s->channels == 2);
- else {
- /* copy the data but convert it to signed */
- for (i = 0; i < data_size; i++){
- *data++ = buf[i] + 0x80;
- *data++ = buf[i] + 0x80;
- }
- }
- }
+ if (silent_chunks) {
+ memset(data, s->out_bps == 2 ? 0x00 : 0x80, silent_size);
+ data += silent_size;
+ }
+ if (s->avctx->bits_per_coded_sample == 16)
+ vmdaudio_decode_audio(s, data, buf, data_size, s->avctx->channels == 2);
+ else {
+ /* just copy the data */
+ memcpy(data, buf, data_size);
+ }
- return data_size * 2;
+ return silent_size + data_size * s->out_bps;
}
static int vmdaudio_decode_frame(AVCodecContext *avctx,
const uint8_t *buf = avpkt->data;
int buf_size = avpkt->size;
VmdAudioContext *s = avctx->priv_data;
+ int block_type, silent_chunks;
unsigned char *output_samples = (unsigned char *)data;
- /* point to the start of the encoded data */
- const unsigned char *p = buf + 16;
-
- if (buf_size < 16)
+ if (buf_size < 16) {
+ av_log(avctx, AV_LOG_WARNING, "skipping small junk packet\n");
+ *data_size = 0;
return buf_size;
+ }
- if (buf[6] == 1) {
- /* the chunk contains audio */
- *data_size = vmdaudio_loadsound(s, output_samples, p, 0, buf_size - 16);
- } else if (buf[6] == 2) {
- /* initial chunk, may contain audio and silence */
- uint32_t flags = AV_RB32(p);
- int raw_block_size = s->block_align *
- (av_get_bits_per_sample_fmt(avctx->sample_fmt) / 8);
- int silent_chunks;
- if(flags == 0xFFFFFFFF)
- silent_chunks = 32;
- else
- silent_chunks = av_log2(flags + 1);
- if(*data_size < (s->block_align*silent_chunks + buf_size - 20) * 2)
- return -1;
- *data_size = 0;
- memset(output_samples, 0, raw_block_size * silent_chunks);
- output_samples += raw_block_size * silent_chunks;
- *data_size = raw_block_size * silent_chunks;
- *data_size += vmdaudio_loadsound(s, output_samples, p + 4, 0, buf_size - 20);
- } else if (buf[6] == 3) {
- /* silent chunk */
- *data_size = vmdaudio_loadsound(s, output_samples, p, 1, 0);
+ block_type = buf[6];
+ if (block_type < BLOCK_TYPE_AUDIO || block_type > BLOCK_TYPE_SILENCE) {
+ av_log(avctx, AV_LOG_ERROR, "unknown block type: %d\n", block_type);
+ return AVERROR(EINVAL);
+ }
+ buf += 16;
+ buf_size -= 16;
+
+ silent_chunks = 0;
+ if (block_type == BLOCK_TYPE_INITIAL) {
+ uint32_t flags = AV_RB32(buf);
+ silent_chunks = av_popcount(flags);
+ buf += 4;
+ buf_size -= 4;
+ } else if (block_type == BLOCK_TYPE_SILENCE) {
+ silent_chunks = 1;
+ buf_size = 0; // should already be zero but set it just to be sure
}
- return buf_size;
+ /* ensure output buffer is large enough */
+ if (*data_size < (avctx->block_align*silent_chunks + buf_size) * s->out_bps)
+ return -1;
+
+ *data_size = vmdaudio_loadsound(s, output_samples, buf, silent_chunks, buf_size);
+
+ return avpkt->size;
}