Justin Ruggles <[email protected]> writes:
> This ensures that any processing between the MDCT and exponent extraction will
> be using clipped coefficients.
> ---
> libavcodec/ac3enc.c | 10 +++++++++-
> libavcodec/ac3enc.h | 8 ++++++++
> libavcodec/ac3enc_template.c | 16 +++++++++++++++-
> 3 files changed, 32 insertions(+), 2 deletions(-)
>
>
> diff --git a/libavcodec/ac3enc.c b/libavcodec/ac3enc.c
> index 3426bd2..e5e2edc 100644
> --- a/libavcodec/ac3enc.c
> +++ b/libavcodec/ac3enc.c
> @@ -1898,7 +1898,10 @@ int ff_ac3_encode_frame(AVCodecContext *avctx,
> unsigned char *frame,
>
> s->apply_mdct(s);
>
> - s->scale_coefficients(s);
> + if (s->fixed_point)
> + s->scale_coefficients(s);
> +
> + s->clip_coefficients(s);
>
> s->cpl_on = s->cpl_enabled;
> compute_coupling_strategy(s);
> @@ -1908,6 +1911,9 @@ int ff_ac3_encode_frame(AVCodecContext *avctx, unsigned
> char *frame,
>
> s->compute_rematrixing_strategy(s);
>
> + if (!s->fixed_point)
> + s->scale_coefficients(s);
> +
> apply_rematrixing(s);
>
> process_exponents(s);
> @@ -2354,6 +2360,7 @@ av_cold int ff_ac3_encode_init(AVCodecContext *avctx)
> s->allocate_sample_buffers =
> ff_ac3_fixed_allocate_sample_buffers;
> s->deinterleave_input_samples =
> ff_ac3_fixed_deinterleave_input_samples;
> s->apply_mdct = ff_ac3_fixed_apply_mdct;
> + s->clip_coefficients = ff_ac3_fixed_clip_coefficients;
> s->apply_channel_coupling =
> ff_ac3_fixed_apply_channel_coupling;
> s->compute_rematrixing_strategy =
> ff_ac3_fixed_compute_rematrixing_strategy;
> } else if (CONFIG_AC3_ENCODER || CONFIG_EAC3_ENCODER) {
> @@ -2364,6 +2371,7 @@ av_cold int ff_ac3_encode_init(AVCodecContext *avctx)
> s->allocate_sample_buffers =
> ff_ac3_float_allocate_sample_buffers;
> s->deinterleave_input_samples =
> ff_ac3_float_deinterleave_input_samples;
> s->apply_mdct = ff_ac3_float_apply_mdct;
> + s->clip_coefficients = ff_ac3_float_clip_coefficients;
> s->apply_channel_coupling =
> ff_ac3_float_apply_channel_coupling;
> s->compute_rematrixing_strategy =
> ff_ac3_float_compute_rematrixing_strategy;
> }
> diff --git a/libavcodec/ac3enc.h b/libavcodec/ac3enc.h
> index bf25298..ff8a389 100644
> --- a/libavcodec/ac3enc.h
> +++ b/libavcodec/ac3enc.h
> @@ -50,12 +50,16 @@
> #if CONFIG_AC3ENC_FLOAT
> #define AC3_NAME(x) ff_ac3_float_ ## x
> #define MAC_COEF(d,a,b) ((d)+=(a)*(b))
> +#define COEF_MIN (-16777215.0/16777216.0)
> +#define COEF_MAX ( 16777215.0/16777216.0)
Why that range?
> typedef float SampleType;
> typedef float CoefType;
> typedef float CoefSumType;
> #else
> #define AC3_NAME(x) ff_ac3_fixed_ ## x
> #define MAC_COEF(d,a,b) MAC64(d,a,b)
> +#define COEF_MIN -16777215
> +#define COEF_MAX 16777215
> typedef int16_t SampleType;
> typedef int32_t CoefType;
> typedef int64_t CoefSumType;
> @@ -235,6 +239,7 @@ typedef struct AC3EncodeContext {
> void (*deinterleave_input_samples)(struct AC3EncodeContext *s,
> const SampleType *samples);
> void (*apply_mdct)(struct AC3EncodeContext *s);
> + void (*clip_coefficients)(struct AC3EncodeContext *s);
> void (*apply_channel_coupling)(struct AC3EncodeContext *s);
> void (*compute_rematrixing_strategy)(struct AC3EncodeContext *s);
>
> @@ -289,6 +294,9 @@ void
> ff_ac3_float_deinterleave_input_samples(AC3EncodeContext *s,
> void ff_ac3_fixed_apply_mdct(AC3EncodeContext *s);
> void ff_ac3_float_apply_mdct(AC3EncodeContext *s);
>
> +void ff_ac3_fixed_clip_coefficients(AC3EncodeContext *s);
> +void ff_ac3_float_clip_coefficients(AC3EncodeContext *s);
> +
> void ff_ac3_fixed_apply_channel_coupling(AC3EncodeContext *s);
> void ff_ac3_float_apply_channel_coupling(AC3EncodeContext *s);
>
> diff --git a/libavcodec/ac3enc_template.c b/libavcodec/ac3enc_template.c
> index f6248a8..2e4b01a 100644
> --- a/libavcodec/ac3enc_template.c
> +++ b/libavcodec/ac3enc_template.c
> @@ -107,6 +107,20 @@ void AC3_NAME(apply_mdct)(AC3EncodeContext *s)
> }
>
> +void AC3_NAME(clip_coefficients)(AC3EncodeContext *s)
> +{
> +#if CONFIG_AC3ENC_FLOAT
> +#define vector_clip_coef s->dsp.vector_clipf
> +#else
> +#define vector_clip_coef s->dsp.vector_clip_int32
> +#endif
> + int chan_size = AC3_MAX_COEFS * AC3_MAX_BLOCKS;
> + vector_clip_coef(s->mdct_coef_buffer + chan_size,
> + s->mdct_coef_buffer + chan_size,
> + COEF_MIN, COEF_MAX, chan_size * s->channels);
> +}
Would it perhaps be prettier to put this function in the _fixed/float.c
files instead?
> +
> /**
> * Calculate a single coupling coordinate.
> */
> @@ -161,7 +175,7 @@ void AC3_NAME(apply_channel_coupling)(AC3EncodeContext *s)
> }
>
> /* coefficients must be clipped to +/- 1.0 in order to be encoded */
> - s->dsp.vector_clipf(cpl_coef, cpl_coef, -1.0f, 1.0f, num_cpl_coefs);
> + s->dsp.vector_clipf(cpl_coef, cpl_coef, COEF_MIN, COEF_MAX,
> num_cpl_coefs);
That comment is slightly inaccurate now, but I guess it doesn't really
matter.
> /* scale coupling coefficients from float to 24-bit fixed-point */
> s->ac3dsp.float_to_fixed24(&block->fixed_coef[CPL_CH][cpl_start],
Looks OK otherwise.
--
Måns Rullgård
[email protected]
_______________________________________________
libav-devel mailing list
[email protected]
https://lists.libav.org/mailman/listinfo/libav-devel
