[FFmpeg-cvslog] alac: split element parsing into a separate function
Justin Ruggles
git at videolan.org
Thu Jul 19 23:35:55 CEST 2012
ffmpeg | branch: master | Justin Ruggles <justin.ruggles at gmail.com> | Mon Jul 9 16:05:53 2012 -0400| [81c9e2e6d074ccbf94e19c67d38b7b62e7c3f820] | committer: Justin Ruggles
alac: split element parsing into a separate function
This will make multi-channel implementation simpler.
Based partially on a patch by Andrew D'Addesio <modchipv12 at gmail.com>.
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=81c9e2e6d074ccbf94e19c67d38b7b62e7c3f820
---
libavcodec/alac.c | 121 +++++++++++++++++++++++++++++++++++------------------
1 file changed, 81 insertions(+), 40 deletions(-)
diff --git a/libavcodec/alac.c b/libavcodec/alac.c
index b44b5c4..1e37290 100644
--- a/libavcodec/alac.c
+++ b/libavcodec/alac.c
@@ -78,6 +78,18 @@ typedef struct {
int nb_samples; /**< number of samples in the current frame */
} ALACContext;
+enum RawDataBlockType {
+ /* At the moment, only SCE, CPE, LFE, and END are recognized. */
+ TYPE_SCE,
+ TYPE_CPE,
+ TYPE_CCE,
+ TYPE_LFE,
+ TYPE_DSE,
+ TYPE_PCE,
+ TYPE_FIL,
+ TYPE_END
+};
+
static inline unsigned int decode_scalar(GetBitContext *gb, int k,
int readsamplesize)
{
@@ -268,27 +280,18 @@ static void append_extra_bits(int32_t *buffer[MAX_CHANNELS],
buffer[ch][i] = (buffer[ch][i] << extra_bits) | extra_bits_buffer[ch][i];
}
-static int alac_decode_frame(AVCodecContext *avctx, void *data,
- int *got_frame_ptr, AVPacket *avpkt)
+static int decode_element(AVCodecContext *avctx, void *data, int ch_index,
+ int channels)
{
ALACContext *alac = avctx->priv_data;
-
- int channels;
int hassize;
unsigned int readsamplesize;
int is_compressed;
uint8_t interlacing_shift;
uint8_t interlacing_leftweight;
+ uint32_t output_samples;
int i, ch, ret;
- init_get_bits(&alac->gb, avpkt->data, avpkt->size * 8);
-
- channels = get_bits(&alac->gb, 3) + 1;
- if (channels != avctx->channels) {
- av_log(avctx, AV_LOG_ERROR, "frame header channel count mismatch\n");
- return AVERROR_INVALIDDATA;
- }
-
skip_bits(&alac->gb, 4); /* element instance tag */
skip_bits(&alac->gb, 12); /* unused header bits */
@@ -305,28 +308,32 @@ static int alac_decode_frame(AVCodecContext *avctx, void *data,
/* whether the frame is compressed */
is_compressed = !get_bits1(&alac->gb);
- if (hassize) {
- /* now read the number of samples as a 32bit integer */
- uint32_t output_samples = get_bits_long(&alac->gb, 32);
- if (!output_samples || output_samples > alac->max_samples_per_frame) {
- av_log(avctx, AV_LOG_ERROR, "invalid samples per frame: %d\n",
- output_samples);
- return AVERROR_INVALIDDATA;
- }
- alac->nb_samples = output_samples;
- } else
- alac->nb_samples = alac->max_samples_per_frame;
-
- /* get output buffer */
- alac->frame.nb_samples = alac->nb_samples;
- if ((ret = avctx->get_buffer(avctx, &alac->frame)) < 0) {
- av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
- return ret;
+ if (hassize)
+ output_samples = get_bits_long(&alac->gb, 32);
+ else
+ output_samples = alac->max_samples_per_frame;
+ if (!output_samples || output_samples > alac->max_samples_per_frame) {
+ av_log(avctx, AV_LOG_ERROR, "invalid samples per frame: %d\n",
+ output_samples);
+ return AVERROR_INVALIDDATA;
}
- if (alac->sample_size > 16) {
- for (ch = 0; ch < alac->channels; ch++)
- alac->output_samples_buffer[ch] = (int32_t *)alac->frame.data[ch];
+ if (!alac->nb_samples) {
+ /* get output buffer */
+ alac->frame.nb_samples = output_samples;
+ if ((ret = avctx->get_buffer(avctx, &alac->frame)) < 0) {
+ av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
+ return ret;
+ }
+ if (alac->sample_size > 16) {
+ for (ch = 0; ch < channels; ch++)
+ alac->output_samples_buffer[ch] = (int32_t *)alac->frame.data[ch_index + ch];
+ }
+ } else if (output_samples != alac->nb_samples) {
+ av_log(avctx, AV_LOG_ERROR, "sample count mismatch: %u != %d\n",
+ output_samples, alac->nb_samples);
+ return AVERROR_INVALIDDATA;
}
+ alac->nb_samples = output_samples;
if (is_compressed) {
int16_t predictor_coef_table[MAX_CHANNELS][32];
@@ -391,16 +398,13 @@ static int alac_decode_frame(AVCodecContext *avctx, void *data,
/* not compressed, easy case */
for (i = 0; i < alac->nb_samples; i++) {
for (ch = 0; ch < channels; ch++) {
- alac->output_samples_buffer[ch][i] = get_sbits_long(&alac->gb,
- alac->sample_size);
+ alac->output_samples_buffer[ch][i] = get_sbits_long(&alac->gb, alac->sample_size);
}
}
alac->extra_bits = 0;
interlacing_shift = 0;
interlacing_leftweight = 0;
}
- if (get_bits(&alac->gb, 3) != 7)
- av_log(avctx, AV_LOG_ERROR, "Error : Wrong End Of Frame\n");
if (channels == 2 && interlacing_leftweight) {
decorrelate_stereo(alac->output_samples_buffer, alac->nb_samples,
@@ -409,25 +413,62 @@ static int alac_decode_frame(AVCodecContext *avctx, void *data,
if (alac->extra_bits) {
append_extra_bits(alac->output_samples_buffer, alac->extra_bits_buffer,
- alac->extra_bits, alac->channels, alac->nb_samples);
+ alac->extra_bits, channels, alac->nb_samples);
}
switch(alac->sample_size) {
case 16: {
- for (ch = 0; ch < alac->channels; ch++) {
- int16_t *outbuffer = (int16_t *)alac->frame.data[ch];
+ for (ch = 0; ch < channels; ch++) {
+ int16_t *outbuffer = (int16_t *)alac->frame.data[ch_index + ch];
for (i = 0; i < alac->nb_samples; i++)
*outbuffer++ = alac->output_samples_buffer[ch][i];
}}
break;
case 24: {
- for (ch = 0; ch < alac->channels; ch++) {
+ for (ch = 0; ch < channels; ch++) {
for (i = 0; i < alac->nb_samples; i++)
alac->output_samples_buffer[ch][i] <<= 8;
}}
break;
}
+ return 0;
+}
+
+static int alac_decode_frame(AVCodecContext *avctx, void *data,
+ int *got_frame_ptr, AVPacket *avpkt)
+{
+ ALACContext *alac = avctx->priv_data;
+ enum RawDataBlockType element;
+ int channels;
+ int ch, ret;
+
+ init_get_bits(&alac->gb, avpkt->data, avpkt->size * 8);
+
+ alac->nb_samples = 0;
+ ch = 0;
+ while (get_bits_left(&alac->gb)) {
+ element = get_bits(&alac->gb, 3);
+ if (element == TYPE_END)
+ break;
+ if (element > TYPE_CPE && element != TYPE_LFE) {
+ av_log(avctx, AV_LOG_ERROR, "syntax element unsupported: %d", element);
+ return AVERROR_PATCHWELCOME;
+ }
+
+ channels = (element == TYPE_CPE) ? 2 : 1;
+ if (ch + channels > alac->channels) {
+ av_log(avctx, AV_LOG_ERROR, "invalid element channel count\n");
+ return AVERROR_INVALIDDATA;
+ }
+
+ ret = decode_element(avctx, data, ch, channels);
+ if (ret < 0)
+ return ret;
+
+ ch += channels;
+ }
+
if (avpkt->size * 8 - get_bits_count(&alac->gb) > 8)
av_log(avctx, AV_LOG_ERROR, "Error : %d bits left\n",
avpkt->size * 8 - get_bits_count(&alac->gb));
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