[FFmpeg-devel] [PATCH] E-AC-3 spectral extension

[Justin Ruggles]

Michael Niedermayer wrote:
> On Tue, Jun 02, 2009 at 09:19:23PM -0400, Justin Ruggles wrote:
> [...]
>> -    /* TODO: spectral extension coordinates */
>> +    /* spectral extension coordinates */
>> +    if (s->spx_in_use) {
>> +        for (ch = 1; ch <= fbw_channels; ch++) {
>> +            if (s->channel_in_spx[ch]) {
>> +                if (s->first_spx_coords[ch] || get_bits1(gbc)) {
>> +                    int bin;
>> +                    float spx_blend;
>> +                    int master_spx_coord;
>> +                    s->first_spx_coords[ch] = 0;
>> +                    spx_blend = get_bits(gbc, 5) * 0.03125f;
>> +                    master_spx_coord = get_bits(gbc, 2) * 3;
>> +                    bin = s->spx_start_freq;
> 
> an empty line in there somewhere would improve readability IMHO

fixed.

> [...]
>> +                        /* decode spx coordinates */
>> +                        spx_coord_exp  = get_bits(gbc, 4);
>> +                        spx_coord_mant = get_bits(gbc, 2);
>> +                        if (spx_coord_exp == 15)
>> +                            spx_coord = spx_coord_mant * 8.0f;
>> +                        else
>> +                            spx_coord = (spx_coord_mant + 4) * 4.0f;
>> +                        spx_coord /= 1 << (spx_coord_exp + master_spx_coord);
> 
> something based on the following would avoid the /
> spx_coord *= (1<<123) >> (spx_coord_exp + master_spx_coord)
> 
> also *4 can be factored out of the if/else and into the factor above

fixed (I think).

> [...]
>> @@ -66,6 +62,96 @@ typedef enum {
>>  
>>  #define EAC3_SR_CODE_REDUCED  3
>>  
>> +void ff_eac3_apply_spectral_extension(AC3DecodeContext *s)
>> +{
>> +    int bin, bnd, ch, i;
> 
>> +    uint8_t wrapflag[SPX_MAX_BANDS]={0,}, num_copy_sections, copy_sizes[SPX_MAX_BANDS];
>> +    float rms_energy[SPX_MAX_BANDS];
>> +
>> +    /* Set copy index mapping table. Set wrap flags to apply a notch filter at
>> +       wrap points later on. */
>> +    wrapflag[0] = 1;
> 
> double initialization

fixed.

>> +    bin = s->spx_copy_start_freq;
>> +    num_copy_sections = 0;
>> +    for (bnd = 0; bnd < s->num_spx_bands; bnd++) {
>> +        int copysize;
>> +        int bandsize = s->spx_band_sizes[bnd];
> 
>> +        if ((bin + bandsize) > s->spx_start_freq) {
> 
> redundant ()

fixed.

New patch attached.

Thanks,
Justin