Christophe Gisquet:
> Summary of changes
> - move back to regular, non-macro, get_bits API
> - reduce the lookup to switch the coding method
> - shorter reads wherever possible, in particular for the end of bitstream
> (16 bits instead of 32, as per the above)
>
> There are cases that really need longer lengths (larger EG codes) of up
> to 27 bits.
>
> Win64: 6.10 -> 4.87 (~20% speedup)
>
> Reference for an hypothetical 32bits version of the cached reader:
> Win32: 11.4 -> 9.8 (14%, because iDCT is not SIMDed)
> ---
The commit message claims to fix something; what does it fix?
Also, changing to the non-macro API should be done in a separate commit
to the one changing the type of bitstream reader.
Furthermore, you should also provide information about the code size
impact when switching the type of reader.
> libavcodec/proresdec2.c | 53 ++++++++++++++++++-----------------------
> 1 file changed, 23 insertions(+), 30 deletions(-)
>
> diff --git a/libavcodec/proresdec2.c b/libavcodec/proresdec2.c
> index 9297860946..6e243cfc17 100644
> --- a/libavcodec/proresdec2.c
> +++ b/libavcodec/proresdec2.c
> @@ -24,9 +24,7 @@
> * Known FOURCCs: 'apch' (HQ), 'apcn' (SD), 'apcs' (LT), 'apco' (Proxy),
> 'ap4h' (4444), 'ap4x' (4444 XQ)
> */
>
> -//#define DEBUG
> -
> -#define LONG_BITSTREAM_READER
> +#define CACHED_BITSTREAM_READER 1
>
> #include "config_components.h"
>
> @@ -422,35 +420,37 @@ static int decode_picture_header(AVCodecContext *avctx,
> const uint8_t *buf, cons
> return pic_data_size;
> }
>
> -#define DECODE_CODEWORD(val, codebook, SKIP) \
> +/* bitstream_read may fail on 32bits ARCHS for >24 bits, so use long version
> there */
> +#if 0 //BITSTREAM_BITS == 32
> +# define READ_BITS get_bits_long
> +#else
> +# define READ_BITS get_bits
> +#endif
> +
> +#define DECODE_CODEWORD(val, codebook) \
> do { \
> unsigned int rice_order, exp_order, switch_bits; \
> unsigned int q, buf, bits; \
> \
> - UPDATE_CACHE(re, gb); \
> - buf = GET_CACHE(re, gb); \
> + buf = show_bits(gb, 14); \
> \
> /* number of bits to switch between rice and exp golomb */ \
> switch_bits = codebook & 3; \
> rice_order = codebook >> 5; \
> exp_order = (codebook >> 2) & 7; \
> \
> - q = 31 - av_log2(buf); \
> + q = 13 - av_log2(buf); \
> \
> if (q > switch_bits) { /* exp golomb */ \
> bits = exp_order - switch_bits + (q<<1); \
> - if (bits > FFMIN(MIN_CACHE_BITS, 31)) \
> - return AVERROR_INVALIDDATA; \
> - val = SHOW_UBITS(re, gb, bits) - (1 << exp_order) + \
> + val = READ_BITS(gb, bits) - (1 << exp_order) + \
> ((switch_bits + 1) << rice_order); \
> - SKIP(re, gb, bits); \
> } else if (rice_order) { \
> - SKIP_BITS(re, gb, q+1); \
> - val = (q << rice_order) + SHOW_UBITS(re, gb, rice_order); \
> - SKIP(re, gb, rice_order); \
> + skip_remaining(gb, q+1); \
> + val = (q << rice_order) + get_bits(gb, rice_order); \
> } else { \
> val = q; \
> - SKIP(re, gb, q+1); \
> + skip_remaining(gb, q+1); \
> } \
> } while (0)
>
> @@ -466,9 +466,7 @@ static av_always_inline int
> decode_dc_coeffs(GetBitContext *gb, int16_t *out,
> int16_t prev_dc;
> int code, i, sign;
>
> - OPEN_READER(re, gb);
> -
> - DECODE_CODEWORD(code, FIRST_DC_CB, LAST_SKIP_BITS);
> + DECODE_CODEWORD(code, FIRST_DC_CB);
> prev_dc = TOSIGNED(code);
> out[0] = prev_dc;
>
> @@ -477,13 +475,12 @@ static av_always_inline int
> decode_dc_coeffs(GetBitContext *gb, int16_t *out,
> code = 5;
> sign = 0;
> for (i = 1; i < blocks_per_slice; i++, out += 64) {
> - DECODE_CODEWORD(code, dc_codebook[FFMIN(code, 6U)], LAST_SKIP_BITS);
> + DECODE_CODEWORD(code, dc_codebook[FFMIN(code, 6U)]);
> if(code) sign ^= -(code & 1);
> else sign = 0;
> prev_dc += (((code + 1) >> 1) ^ sign) - sign;
> out[0] = prev_dc;
> }
> - CLOSE_READER(re, gb);
> return 0;
> }
>
> @@ -497,11 +494,9 @@ static av_always_inline int
> decode_ac_coeffs(AVCodecContext *avctx, GetBitContex
> const ProresContext *ctx = avctx->priv_data;
> int block_mask, sign;
> unsigned pos, run, level;
> - int max_coeffs, i, bits_left;
> + int max_coeffs, i, bits_rem;
> int log2_block_count = av_log2(blocks_per_slice);
>
> - OPEN_READER(re, gb);
> - UPDATE_CACHE(re, gb); \
> run = 4;
> level = 2;
>
> @@ -509,28 +504,26 @@ static av_always_inline int
> decode_ac_coeffs(AVCodecContext *avctx, GetBitContex
> block_mask = blocks_per_slice - 1;
>
> for (pos = block_mask;;) {
> - bits_left = gb->size_in_bits - re_index;
> - if (!bits_left || (bits_left < 32 && !SHOW_UBITS(re, gb, bits_left)))
> + bits_rem = get_bits_left(gb);
> + if (!bits_rem || (bits_rem < 16 && !show_bits(gb, bits_rem)))
> break;
>
> - DECODE_CODEWORD(run, run_to_cb[FFMIN(run, 15)], LAST_SKIP_BITS);
> + DECODE_CODEWORD(run, run_to_cb[FFMIN(run, 15)]);
> pos += run + 1;
> if (pos >= max_coeffs) {
> av_log(avctx, AV_LOG_ERROR, "ac tex damaged %d, %d\n", pos,
> max_coeffs);
> return AVERROR_INVALIDDATA;
> }
>
> - DECODE_CODEWORD(level, lev_to_cb[FFMIN(level, 9)], SKIP_BITS);
> + DECODE_CODEWORD(level, lev_to_cb[FFMIN(level, 9)]);
> level += 1;
>
> i = pos >> log2_block_count;
>
> - sign = SHOW_SBITS(re, gb, 1);
> - SKIP_BITS(re, gb, 1);
> + sign = -get_bits1(gb);
> out[((pos & block_mask) << 6) + ctx->scan[i]] = ((level ^ sign) -
> sign);
> }
>
> - CLOSE_READER(re, gb);
> return 0;
> }
>
_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
To unsubscribe, visit link above, or email
ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
