[FFmpeg-devel] [PATCH 4/8] sbc: implement SBC encoder (low-complexity subband codec)

Michael Niedermayer michael at niedermayer.cc
Mon Dec 18 13:45:12 EET 2017


On Sun, Dec 17, 2017 at 10:47:16PM +0100, Aurelien Jacobs wrote:
> This was originally based on libsbc, and was fully integrated into ffmpeg.
> ---
[...]
> +static inline void sbc_analyze_4b_4s_simd(SBCDSPContext *s,
> +                                          int16_t *x, int32_t *out, int out_stride)
> +{
> +    /* Analyze blocks */
> +    s->sbc_analyze_4(x + 12, out, ff_sbcdsp_analysis_consts_fixed4_simd_odd);
> +    out += out_stride;
> +    s->sbc_analyze_4(x + 8, out, ff_sbcdsp_analysis_consts_fixed4_simd_even);
> +    out += out_stride;
> +    s->sbc_analyze_4(x + 4, out, ff_sbcdsp_analysis_consts_fixed4_simd_odd);
> +    out += out_stride;
> +    s->sbc_analyze_4(x + 0, out, ff_sbcdsp_analysis_consts_fixed4_simd_even);
> +
> +    emms_c();
> +}
> +
> +static inline void sbc_analyze_4b_8s_simd(SBCDSPContext *s,
> +                                          int16_t *x, int32_t *out, int out_stride)
> +{
> +    /* Analyze blocks */
> +    s->sbc_analyze_8(x + 24, out, ff_sbcdsp_analysis_consts_fixed8_simd_odd);
> +    out += out_stride;
> +    s->sbc_analyze_8(x + 16, out, ff_sbcdsp_analysis_consts_fixed8_simd_even);
> +    out += out_stride;
> +    s->sbc_analyze_8(x + 8, out, ff_sbcdsp_analysis_consts_fixed8_simd_odd);
> +    out += out_stride;
> +    s->sbc_analyze_8(x + 0, out, ff_sbcdsp_analysis_consts_fixed8_simd_even);
> +
> +    emms_c();
> +}
> +
> +static inline void sbc_analyze_1b_8s_simd_even(SBCDSPContext *s,
> +                                               int16_t *x, int32_t *out,
> +                                               int out_stride);
> +
> +static inline void sbc_analyze_1b_8s_simd_odd(SBCDSPContext *s,
> +                                              int16_t *x, int32_t *out,
> +                                              int out_stride)
> +{
> +    s->sbc_analyze_8(x, out, ff_sbcdsp_analysis_consts_fixed8_simd_odd);
> +    s->sbc_analyze_8s = sbc_analyze_1b_8s_simd_even;
> +
> +    emms_c();
> +}
> +
> +static inline void sbc_analyze_1b_8s_simd_even(SBCDSPContext *s,
> +                                               int16_t *x, int32_t *out,
> +                                               int out_stride)
> +{
> +    s->sbc_analyze_8(x, out, ff_sbcdsp_analysis_consts_fixed8_simd_even);
> +    s->sbc_analyze_8s = sbc_analyze_1b_8s_simd_odd;
> +
> +    emms_c();
> +}

at least some of the functions are always called in a loop, the emms_c() could
be called after the loop


[...]
> diff --git a/libavcodec/sbcdsp_data.c b/libavcodec/sbcdsp_data.c
> new file mode 100644
> index 0000000000..1e19b9d9d1
> --- /dev/null
> +++ b/libavcodec/sbcdsp_data.c
> @@ -0,0 +1,329 @@
> +/*
> + * Bluetooth low-complexity, subband codec (SBC)
> + *
> + * Copyright (C) 2017  Aurelien Jacobs <aurel at gnuage.org>
> + * Copyright (C) 2008-2010  Nokia Corporation
> + * Copyright (C) 2004-2010  Marcel Holtmann <marcel at holtmann.org>
> + * Copyright (C) 2004-2005  Henryk Ploetz <henryk at ploetzli.ch>
> + * Copyright (C) 2005-2006  Brad Midgley <bmidgley at xmission.com>
> + *
> + * This file is part of FFmpeg.
> + *
> + * FFmpeg is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * FFmpeg is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with FFmpeg; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
> + */
> +
> +/**
> + * @file
> + * miscellaneous SBC tables
> + */
> +
> +#include "sbcdsp_data.h"
> +
> +#define F_PROTO(x) (int32_t) ((x * 2) * ((int32_t) 1 << 15) + 0.5)
> +#define F_COS(x)   (int32_t) ((x    ) * ((int32_t) 1 << 15) + 0.5)

this needs more () to protect the argument x and the whole expression
for example F_PROTO(1+1) would produce unexpected results

thanks

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

What does censorship reveal? It reveals fear. -- Julian Assange
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