/**
* Adjust the frame size to make the average bit rate match the target bit rate.
* This is only needed for 11025, 22050, and 44100 sample rates or any E-AC-3.
+ *
+ * @param s AC-3 encoder private context
*/
void ff_ac3_adjust_frame_size(AC3EncodeContext *s)
{
}
+/**
+ * Set the initial coupling strategy parameters prior to coupling analysis.
+ *
+ * @param s AC-3 encoder private context
+ */
void ff_ac3_compute_coupling_strategy(AC3EncodeContext *s)
{
int blk, ch;
/**
* Apply stereo rematrixing to coefficients based on rematrixing flags.
+ *
+ * @param s AC-3 encoder private context
*/
void ff_ac3_apply_rematrixing(AC3EncodeContext *s)
{
}
-/**
+/*
* Initialize exponent tables.
*/
static av_cold void exponent_init(AC3EncodeContext *s)
}
-/**
+/*
* Extract exponents from the MDCT coefficients.
*/
static void extract_exponents(AC3EncodeContext *s)
{ EXP_D45, EXP_D25, EXP_D25, EXP_D15, EXP_D15, EXP_D15 }
};
-/**
+/*
* Calculate exponent strategies for all channels.
* Array arrangement is reversed to simplify the per-channel calculation.
*/
/**
* Update the exponents so that they are the ones the decoder will decode.
+ *
+ * @param[in,out] exp array of exponents for 1 block in 1 channel
+ * @param nb_exps number of exponents in active bandwidth
+ * @param exp_strategy exponent strategy for the block
+ * @param cpl indicates if the block is in the coupling channel
*/
static void encode_exponents_blk_ch(uint8_t *exp, int nb_exps, int exp_strategy,
int cpl)
}
-/**
+/*
* Encode exponents from original extracted form to what the decoder will see.
* This copies and groups exponents based on exponent strategy and reduces
* deltas between adjacent exponent groups so that they can be differentially
}
-/**
+/*
* Count exponent bits based on bandwidth, coupling, and exponent strategies.
*/
static int count_exponent_bits(AC3EncodeContext *s)
* Group exponents.
* 3 delta-encoded exponents are in each 7-bit group. The number of groups
* varies depending on exponent strategy and bandwidth.
+ *
+ * @param s AC-3 encoder private context
*/
void ff_ac3_group_exponents(AC3EncodeContext *s)
{
* Calculate final exponents from the supplied MDCT coefficients and exponent shift.
* Extract exponents from MDCT coefficients, calculate exponent strategies,
* and encode final exponents.
+ *
+ * @param s AC-3 encoder private context
*/
void ff_ac3_process_exponents(AC3EncodeContext *s)
{
}
-/**
+/*
* Count frame bits that are based solely on fixed parameters.
* This only has to be run once when the encoder is initialized.
*/
}
-/**
+/*
* Initialize bit allocation.
* Set default parameter codes and calculate parameter values.
*/
}
-/**
+/*
* Count the bits used to encode the frame, minus exponents and mantissas.
* 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.
}
-/**
+/*
* Calculate masking curve based on the final exponents.
* Also calculate the power spectral densities to use in future calculations.
*/
}
-/**
+/*
* Ensure that bap for each block and channel point to the current bap_buffer.
* They may have been switched during the bit allocation search.
*/
* Initialize mantissa counts.
* These are set so that they are padded to the next whole group size when bits
* are counted in compute_mantissa_size.
+ *
+ * @param[in,out] mant_cnt running counts for each bap value for each block
*/
static void count_mantissa_bits_init(uint16_t mant_cnt[AC3_MAX_BLOCKS][16])
{
/**
* Update mantissa bit counts for all blocks in 1 channel in a given bandwidth
* range.
+ *
+ * @param s AC-3 encoder private context
+ * @param ch channel index
+ * @param[in,out] mant_cnt running counts for each bap value for each block
+ * @param start starting coefficient bin
+ * @param end ending coefficient bin
*/
static void count_mantissa_bits_update_ch(AC3EncodeContext *s, int ch,
uint16_t mant_cnt[AC3_MAX_BLOCKS][16],
}
-/**
+/*
* Count the number of mantissa bits in the frame based on the bap values.
*/
static int count_mantissa_bits(AC3EncodeContext *s)
* Run the bit allocation with a given SNR offset.
* This calculates the bit allocation pointers that will be used to determine
* the quantization of each mantissa.
+ *
+ * @param s AC-3 encoder private context
+ * @param snr_offset SNR offset, 0 to 1023
* @return the number of bits needed for mantissas if the given SNR offset is
* is used.
*/
}
-/**
+/*
* Constant bitrate bit allocation search.
* Find the largest SNR offset that will allow data to fit in the frame.
*/
}
-/**
+/*
* Perform bit allocation search.
* Finds the SNR offset value that maximizes quality and fits in the specified
* frame size. Output is the SNR offset and a set of bit allocation pointers
/**
* Symmetric quantization on 'levels' levels.
+ *
+ * @param c unquantized coefficient
+ * @param e exponent
+ * @param levels number of quantization levels
+ * @return quantized coefficient
*/
static inline int sym_quant(int c, int e, int levels)
{
/**
* Asymmetric quantization on 2^qbits levels.
+ *
+ * @param c unquantized coefficient
+ * @param e exponent
+ * @param qbits number of quantization bits
+ * @return quantized coefficient
*/
static inline int asym_quant(int c, int e, int qbits)
{
/**
* Quantize a set of mantissas for a single channel in a single block.
+ *
+ * @param s Mantissa count context
+ * @param fixed_coef unquantized fixed-point coefficients
+ * @param exp exponents
+ * @param bap bit allocation pointer indices
+ * @param[out] qmant quantized coefficients
+ * @param start_freq starting coefficient bin
+ * @param end_freq ending coefficient bin
*/
static void quantize_mantissas_blk_ch(AC3Mant *s, int32_t *fixed_coef,
uint8_t *exp, uint8_t *bap,
int i;
for (i = start_freq; i < end_freq; i++) {
- int v;
int c = fixed_coef[i];
int e = exp[i];
- int b = bap[i];
- switch (b) {
- case 0:
- v = 0;
- break;
+ int v = bap[i];
+ if (v)
+ switch (v) {
case 1:
v = sym_quant(c, e, 3);
switch (s->mant1_cnt) {
v = asym_quant(c, e, 16);
break;
default:
- v = asym_quant(c, e, b - 1);
+ v = asym_quant(c, e, v - 1);
break;
}
qmant[i] = v;
/**
* Quantize mantissas using coefficients, exponents, and bit allocation pointers.
+ *
+ * @param s AC-3 encoder private context
*/
void ff_ac3_quantize_mantissas(AC3EncodeContext *s)
{
}
-/**
+/*
* Write the AC-3 frame header to the output bitstream.
*/
static void ac3_output_frame_header(AC3EncodeContext *s)
}
-/**
+/*
* Write one audio block to the output bitstream.
*/
static void output_audio_block(AC3EncodeContext *s, int blk)
}
-/**
+/*
* Fill the end of the frame with 0's and compute the two CRCs.
*/
static void output_frame_end(AC3EncodeContext *s)
/**
* Write the frame to the output bitstream.
+ *
+ * @param s AC-3 encoder private context
+ * @param frame output data buffer
*/
void ff_ac3_output_frame(AC3EncodeContext *s, unsigned char *frame)
{
/**
* Validate metadata options as set by AVOption system.
* These values can optionally be changed per-frame.
+ *
+ * @param s AC-3 encoder private context
*/
int ff_ac3_validate_metadata(AC3EncodeContext *s)
{
/**
* Finalize encoding and free any memory allocated by the encoder.
+ *
+ * @param avctx Codec context
*/
av_cold int ff_ac3_encode_close(AVCodecContext *avctx)
{
}
-/**
+/*
* Set channel information during initialization.
*/
static av_cold int set_channel_info(AC3EncodeContext *s, int channels,
}
-/**
+/*
* Set bandwidth for all channels.
* The user can optionally supply a cutoff frequency. Otherwise an appropriate
* default value will be used.
}
-/**
- * Initialize the encoder.
- */
av_cold int ff_ac3_encode_init(AVCodecContext *avctx)
{
AC3EncodeContext *s = avctx->priv_data;
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