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alac: Convert to the new bitstream reader
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@sasshka @DonDiego
sasshka authored and DonDiego committed Jan 13, 2017
1 parent b1e7394 commit 4795e4f
Showing 1 changed file with 33 additions and 32 deletions.
65 changes: 33 additions & 32 deletions libavcodec/alac.c
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Original file line number Diff line number Diff line change
Expand Up @@ -48,19 +48,20 @@
#include <inttypes.h>

#include "libavutil/channel_layout.h"

#include "avcodec.h"
#include "get_bits.h"
#include "bitstream.h"
#include "bytestream.h"
#include "internal.h"
#include "mathops.h"
#include "unary_legacy.h"
#include "unary.h"
#include "alac_data.h"

#define ALAC_EXTRADATA_SIZE 36

typedef struct ALACContext {
AVCodecContext *avctx;
GetBitContext gb;
BitstreamContext bc;
int channels;

int32_t *predict_error_buffer[2];
Expand All @@ -77,24 +78,24 @@ typedef struct ALACContext {
int nb_samples; /**< number of samples in the current frame */
} ALACContext;

static inline unsigned int decode_scalar(GetBitContext *gb, int k, int bps)
static inline unsigned int decode_scalar(BitstreamContext *bc, int k, int bps)
{
unsigned int x = get_unary_0_9(gb);
unsigned int x = get_unary_0_9(bc);

if (x > 8) { /* RICE THRESHOLD */
/* use alternative encoding */
x = get_bits_long(gb, bps);
x = bitstream_read(bc, bps);
} else if (k != 1) {
int extrabits = show_bits(gb, k);
int extrabits = bitstream_peek(bc, k);

/* multiply x by 2^k - 1, as part of their strange algorithm */
x = (x << k) - x;

if (extrabits > 1) {
x += extrabits - 1;
skip_bits(gb, k);
bitstream_skip(bc, k);
} else
skip_bits(gb, k - 1);
bitstream_skip(bc, k - 1);
}
return x;
}
Expand All @@ -113,7 +114,7 @@ static void rice_decompress(ALACContext *alac, int32_t *output_buffer,
/* calculate rice param and decode next value */
k = av_log2((history >> 9) + 3);
k = FFMIN(k, alac->rice_limit);
x = decode_scalar(&alac->gb, k, bps);
x = decode_scalar(&alac->bc, k, bps);
x += sign_modifier;
sign_modifier = 0;
output_buffer[i] = (x >> 1) ^ -(x & 1);
Expand All @@ -132,7 +133,7 @@ static void rice_decompress(ALACContext *alac, int32_t *output_buffer,
/* calculate rice param and decode block size */
k = 7 - av_log2(history) + ((history + 16) >> 6);
k = FFMIN(k, alac->rice_limit);
block_size = decode_scalar(&alac->gb, k, 16);
block_size = decode_scalar(&alac->bc, k, 16);

if (block_size > 0) {
if (block_size >= nb_samples - i) {
Expand Down Expand Up @@ -257,24 +258,24 @@ static int decode_element(AVCodecContext *avctx, AVFrame *frame, int ch_index,
uint32_t output_samples;
int i, ch;

skip_bits(&alac->gb, 4); /* element instance tag */
skip_bits(&alac->gb, 12); /* unused header bits */
bitstream_skip(&alac->bc, 4); /* element instance tag */
bitstream_skip(&alac->bc, 12); /* unused header bits */

/* the number of output samples is stored in the frame */
has_size = get_bits1(&alac->gb);
has_size = bitstream_read_bit(&alac->bc);

alac->extra_bits = get_bits(&alac->gb, 2) << 3;
alac->extra_bits = bitstream_read(&alac->bc, 2) << 3;
bps = alac->sample_size - alac->extra_bits + channels - 1;
if (bps > 32) {
avpriv_report_missing_feature(avctx, "bps %d", bps);
return AVERROR_PATCHWELCOME;
}

/* whether the frame is compressed */
is_compressed = !get_bits1(&alac->gb);
is_compressed = !bitstream_read_bit(&alac->bc);

if (has_size)
output_samples = get_bits_long(&alac->gb, 32);
output_samples = bitstream_read(&alac->bc, 32);
else
output_samples = alac->max_samples_per_frame;
if (!output_samples || output_samples > alac->max_samples_per_frame) {
Expand Down Expand Up @@ -313,27 +314,27 @@ static int decode_element(AVCodecContext *avctx, AVFrame *frame, int ch_index,
return AVERROR(ENOSYS);
}

decorr_shift = get_bits(&alac->gb, 8);
decorr_left_weight = get_bits(&alac->gb, 8);
decorr_shift = bitstream_read(&alac->bc, 8);
decorr_left_weight = bitstream_read(&alac->bc, 8);

for (ch = 0; ch < channels; ch++) {
prediction_type[ch] = get_bits(&alac->gb, 4);
lpc_quant[ch] = get_bits(&alac->gb, 4);
rice_history_mult[ch] = get_bits(&alac->gb, 3);
lpc_order[ch] = get_bits(&alac->gb, 5);
prediction_type[ch] = bitstream_read(&alac->bc, 4);
lpc_quant[ch] = bitstream_read(&alac->bc, 4);
rice_history_mult[ch] = bitstream_read(&alac->bc, 3);
lpc_order[ch] = bitstream_read(&alac->bc, 5);

if (lpc_order[ch] >= alac->max_samples_per_frame)
return AVERROR_INVALIDDATA;

/* read the predictor table */
for (i = lpc_order[ch] - 1; i >= 0; i--)
lpc_coefs[ch][i] = get_sbits(&alac->gb, 16);
lpc_coefs[ch][i] = bitstream_read_signed(&alac->bc, 16);
}

if (alac->extra_bits) {
for (i = 0; i < alac->nb_samples; i++) {
for (ch = 0; ch < channels; ch++)
alac->extra_bits_buffer[ch][i] = get_bits(&alac->gb, alac->extra_bits);
alac->extra_bits_buffer[ch][i] = bitstream_read(&alac->bc, alac->extra_bits);
}
}
for (ch = 0; ch < channels; ch++) {
Expand Down Expand Up @@ -366,7 +367,7 @@ static int decode_element(AVCodecContext *avctx, AVFrame *frame, int ch_index,
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);
bitstream_read_signed(&alac->bc, alac->sample_size);
}
}
alac->extra_bits = 0;
Expand Down Expand Up @@ -412,13 +413,13 @@ static int alac_decode_frame(AVCodecContext *avctx, void *data,
int channels;
int ch, ret, got_end;

init_get_bits(&alac->gb, avpkt->data, avpkt->size * 8);
bitstream_init8(&alac->bc, avpkt->data, avpkt->size);

got_end = 0;
alac->nb_samples = 0;
ch = 0;
while (get_bits_left(&alac->gb) >= 3) {
element = get_bits(&alac->gb, 3);
while (bitstream_bits_left(&alac->bc) >= 3) {
element = bitstream_read(&alac->bc, 3);
if (element == TYPE_END) {
got_end = 1;
break;
Expand All @@ -438,7 +439,7 @@ static int alac_decode_frame(AVCodecContext *avctx, void *data,
ret = decode_element(avctx, frame,
ff_alac_channel_layout_offsets[alac->channels - 1][ch],
channels);
if (ret < 0 && get_bits_left(&alac->gb))
if (ret < 0 && bitstream_bits_left(&alac->bc))
return ret;

ch += channels;
Expand All @@ -452,9 +453,9 @@ static int alac_decode_frame(AVCodecContext *avctx, void *data,
return AVERROR_INVALIDDATA;
}

if (avpkt->size * 8 - get_bits_count(&alac->gb) > 8) {
if (avpkt->size * 8 - bitstream_tell(&alac->bc) > 8) {
av_log(avctx, AV_LOG_ERROR, "Error : %d bits left\n",
avpkt->size * 8 - get_bits_count(&alac->gb));
avpkt->size * 8 - bitstream_tell(&alac->bc));
}

*got_frame_ptr = 1;
Expand Down

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