---
libavcodec/ac3enc.c | 49 +++++++++++++++++++++++++++++++++++++++++--------
1 files changed, 41 insertions(+), 8 deletions(-)
diff --git libavcodec/ac3enc.c libavcodec/ac3enc.c
index 68ba403..ce5b73a 100644
--- libavcodec/ac3enc.c
+++ libavcodec/ac3enc.c
@@ -68,6 +68,7 @@ typedef struct AC3EncodeContext {
int nb_coefs[AC3_MAX_CHANNELS]; ///< number of frequency coefficients
/* bitrate allocation control */
+ int frame_bits_fixed; ///< number of non-coefficient bits for fixed parameters
int frame_bits; ///< number of non-coefficient bits
int exp_bits; ///< number of bits used by exponents
int slow_gain_code; ///< slow gain code (sgaincod)
@@ -653,13 +654,27 @@ static void set_bit_alloc_params(AC3EncodeContext *s)
s->bit_alloc.floor = ff_ac3_floor_tab[s->floor_code];
}
-static void count_frame_bits(AC3EncodeContext *s,
- uint8_t exp_strategy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS])
+/**
+ * Count frame bits that are based solely on fixed parameters.
+ * This only has to be run once when the encoder is initialized.
+ */
+static void count_frame_bits_fixed(AC3EncodeContext *s)
{
- int blk, ch;
+ int blk;
int frame_bits;
static const int frame_bits_inc[8] = { 0, 0, 2, 2, 2, 4, 2, 4 };
+ /* assumptions:
+ * no dynamic range codes
+ * no channel coupling
+ * no rematrixing
+ * bit allocation parameters do not change between blocks
+ * SNR offsets do not change between blocks
+ * no delta bit allocation
+ * no skipped data
+ * no auxilliary data
+ */
+
/* header size */
frame_bits = 65;
// if (s->channel_mode == 2)
@@ -676,10 +691,6 @@ static void count_frame_bits(AC3EncodeContext *s,
frame_bits += 2 * s->fbw_channels; /* chexpstr[2] * c */
if (s->lfe_on)
frame_bits++; /* lfeexpstr */
- for (ch = 0; ch < s->fbw_channels; ch++) {
- if (exp_strategy[blk][ch] != EXP_REUSE)
- frame_bits += 6 + 2; /* chbwcod[6], gainrng[2] */
- }
frame_bits++; /* baie */
frame_bits++; /* snr */
frame_bits += 2; /* delta / skip */
@@ -697,7 +708,27 @@ static void count_frame_bits(AC3EncodeContext *s,
/* CRC */
frame_bits += 16;
- s->frame_bits = frame_bits;
+ s->frame_bits_fixed = frame_bits;
+}
+
+/**
+ * Count frame bits.
+ * Bits based on fixed parameters have already been counted, so now we just
+ * have to add the bits based on parameters that change during encoding.
+ */
+static void count_frame_bits(AC3EncodeContext *s,
+ uint8_t exp_strategy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS])
+{
+ int blk, ch;
+ int frame_bits = 0;
+
+ for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
+ for (ch = 0; ch < s->fbw_channels; ch++) {
+ if (exp_strategy[blk][ch] != EXP_REUSE)
+ frame_bits += 6 + 2; /* chbwcod[6], gainrng[2] */
+ }
+ }
+ s->frame_bits = s->frame_bits_fixed + frame_bits;
}
/**
@@ -935,6 +966,8 @@ static av_cold int AC3_encode_init(AVCodecContext *avctx)
/* for now bit alloc params do not change so set them here to avoid unnecessary calls */
set_bit_alloc_params(s);
+ count_frame_bits_fixed(s);
+
mdct_init();
for (j = 0; j < 256; j++) {
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