* released under the GPL license.
*/
typedef struct AC3DecodeState {
- uint8_t inbuf[4096]; /* input buffer */
- uint8_t *inbuf_ptr;
- int frame_size;
int flags;
int channels;
a52_state_t* state;
}
#endif
-static int a52_decode_init(AVCodecContext *avctx)
+static av_cold int a52_decode_init(AVCodecContext *avctx)
{
AC3DecodeState *s = avctx->priv_data;
#endif
s->state = s->a52_init(0); /* later use CPU flags */
s->samples = s->a52_samples(s->state);
- s->inbuf_ptr = s->inbuf;
- s->frame_size = 0;
- return 0;
-}
+ /* allow downmixing to stereo or mono */
+ if (avctx->channels > 0 && avctx->request_channels > 0 &&
+ avctx->request_channels < avctx->channels &&
+ avctx->request_channels <= 2) {
+ avctx->channels = avctx->request_channels;
+ }
-/**** the following two functions comes from a52dec */
-static inline int blah (int32_t i)
-{
- if (i > 0x43c07fff)
- return 32767;
- else if (i < 0x43bf8000)
- return -32768;
- return i - 0x43c00000;
+ avctx->sample_fmt = SAMPLE_FMT_S16;
+ return 0;
}
+/**** the following function comes from a52dec */
static inline void float_to_int (float * _f, int16_t * s16, int nchannels)
{
int i, j, c;
nchannels *= 256;
for (i = 0; i < 256; i++) {
for (c = 0; c < nchannels; c += 256)
- s16[j++] = blah (f[i + c]);
+ s16[j++] = av_clip_int16(f[i + c] - 0x43c00000);
}
}
uint8_t *buf, int buf_size)
{
AC3DecodeState *s = avctx->priv_data;
- uint8_t *buf_ptr;
int flags, i, len;
int sample_rate, bit_rate;
short *out_samples = data;
*data_size= 0;
- buf_ptr = buf;
- while (buf_size > 0) {
- len = s->inbuf_ptr - s->inbuf;
- if (s->frame_size == 0) {
- /* no header seen : find one. We need at least 7 bytes to parse it */
- len = HEADER_SIZE - len;
- if (len > buf_size)
- len = buf_size;
- memcpy(s->inbuf_ptr, buf_ptr, len);
- buf_ptr += len;
- s->inbuf_ptr += len;
- buf_size -= len;
- if ((s->inbuf_ptr - s->inbuf) == HEADER_SIZE) {
- len = s->a52_syncinfo(s->inbuf, &s->flags, &sample_rate, &bit_rate);
- if (len == 0) {
- /* no sync found : move by one byte (inefficient, but simple!) */
- memcpy(s->inbuf, s->inbuf + 1, HEADER_SIZE - 1);
- s->inbuf_ptr--;
- } else {
- s->frame_size = len;
- /* update codec info */
- avctx->sample_rate = sample_rate;
- s->channels = ac3_channels[s->flags & 7];
- if (s->flags & A52_LFE)
- s->channels++;
- if (avctx->channels == 0)
- /* No specific number of channel requested */
- avctx->channels = s->channels;
- else if (s->channels < avctx->channels) {
- av_log(avctx, AV_LOG_ERROR, "ac3dec: AC3 Source channels are less than specified: output to %d channels.. (frmsize: %d)\n", s->channels, len);
- avctx->channels = s->channels;
- }
- avctx->bit_rate = bit_rate;
- }
- }
- } else if (len < s->frame_size) {
- len = s->frame_size - len;
- if (len > buf_size)
- len = buf_size;
-
- memcpy(s->inbuf_ptr, buf_ptr, len);
- buf_ptr += len;
- s->inbuf_ptr += len;
- buf_size -= len;
- } else {
- flags = s->flags;
- if (avctx->channels == 1)
- flags = A52_MONO;
- else if (avctx->channels == 2)
- flags = A52_STEREO;
- else
- flags |= A52_ADJUST_LEVEL;
- level = 1;
- if (s->a52_frame(s->state, s->inbuf, &flags, &level, 384)) {
- fail:
- av_log(avctx, AV_LOG_ERROR, "Error decoding frame\n");
- s->inbuf_ptr = s->inbuf;
- s->frame_size = 0;
- continue;
- }
- for (i = 0; i < 6; i++) {
- if (s->a52_block(s->state))
- goto fail;
- float_to_int(s->samples, out_samples + i * 256 * avctx->channels, avctx->channels);
- }
- s->inbuf_ptr = s->inbuf;
- s->frame_size = 0;
- *data_size = 6 * avctx->channels * 256 * sizeof(int16_t);
- break;
- }
+ if (buf_size < HEADER_SIZE) {
+ av_log(avctx, AV_LOG_ERROR, "Error decoding frame, not enough bytes for header\n");
+ return -1;
+ }
+ len = s->a52_syncinfo(buf, &s->flags, &sample_rate, &bit_rate);
+ if (len == 0) {
+ av_log(avctx, AV_LOG_ERROR, "Error decoding frame, no sync byte at begin\n");
+ return -1;
+ }
+ if (buf_size < len) {
+ av_log(avctx, AV_LOG_ERROR, "Error decoding frame, not enough bytes\n");
+ return -1;
+ }
+ /* update codec info */
+ avctx->sample_rate = sample_rate;
+ s->channels = ac3_channels[s->flags & 7];
+ if (s->flags & A52_LFE)
+ s->channels++;
+ if (avctx->request_channels > 0 &&
+ avctx->request_channels <= 2 &&
+ avctx->request_channels < s->channels) {
+ avctx->channels = avctx->request_channels;
+ } else {
+ avctx->channels = s->channels;
+ }
+ avctx->bit_rate = bit_rate;
+ flags = s->flags;
+ if (avctx->channels == 1)
+ flags = A52_MONO;
+ else if (avctx->channels == 2)
+ flags = A52_STEREO;
+ else
+ flags |= A52_ADJUST_LEVEL;
+ level = 1;
+ if (s->a52_frame(s->state, buf, &flags, &level, 384)) {
+ fail:
+ av_log(avctx, AV_LOG_ERROR, "Error decoding frame\n");
+ return -1;
+ }
+ for (i = 0; i < 6; i++) {
+ if (s->a52_block(s->state))
+ goto fail;
+ float_to_int(s->samples, out_samples + i * 256 * avctx->channels, avctx->channels);
}
- return buf_ptr - buf;
+ *data_size = 6 * avctx->channels * 256 * sizeof(int16_t);
+ return len;
}
-static int a52_decode_end(AVCodecContext *avctx)
+static av_cold int a52_decode_end(AVCodecContext *avctx)
{
AC3DecodeState *s = avctx->priv_data;
s->a52_free(s->state);
}
AVCodec liba52_decoder = {
- "ac3",
+ "liba52",
CODEC_TYPE_AUDIO,
CODEC_ID_AC3,
sizeof(AC3DecodeState),
NULL,
a52_decode_end,
a52_decode_frame,
+ .long_name = NULL_IF_CONFIG_SMALL("liba52 ATSC A/52 / AC-3"),
};