diff options
| author | Andreas Rheinhardt <andreas.rheinhardt@gmail.com> | 2020-10-12 05:24:42 +0200 |
|---|---|---|
| committer | Andreas Rheinhardt <andreas.rheinhardt@gmail.com> | 2020-10-12 22:20:37 +0200 |
| commit | 9eb7d8b45d0497d75e5655b79d9eea63bedc833c (patch) | |
| tree | 69f95eb73cc15a457a840c3f915c85edd3ba25ad /libavcodec | |
| parent | e78bbbc2b1e413d11e9edf818e1dc07f16aecf91 (diff) | |
avcodec/vlc, bitstream: Allow to use BE codes to initialize LE VLC
This is easily possible because ff_init_vlc_sparse() already transforms
both LE as well as BE codes to a normal form internally before
processing them further. This will be used in subsequent commits.
Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
Diffstat (limited to 'libavcodec')
| -rw-r--r-- | libavcodec/bitstream.c | 6 | ||||
| -rw-r--r-- | libavcodec/vlc.h | 29 |
2 files changed, 22 insertions, 13 deletions
diff --git a/libavcodec/bitstream.c b/libavcodec/bitstream.c index 95e5092b44..77c2b9ce05 100644 --- a/libavcodec/bitstream.c +++ b/libavcodec/bitstream.c @@ -182,7 +182,7 @@ static int build_table(VLC *vlc, int table_nb_bits, int nb_codes, j = code >> (32 - table_nb_bits); nb = 1 << (table_nb_bits - n); inc = 1; - if (flags & INIT_VLC_LE) { + if (flags & INIT_VLC_OUTPUT_LE) { j = bitswap_32(code); inc = 1 << n; } @@ -217,7 +217,7 @@ static int build_table(VLC *vlc, int table_nb_bits, int nb_codes, subtable_bits = FFMAX(subtable_bits, n); } subtable_bits = FFMIN(subtable_bits, table_nb_bits); - j = (flags & INIT_VLC_LE) ? bitswap_32(code_prefix) >> (32 - table_nb_bits) : code_prefix; + j = (flags & INIT_VLC_OUTPUT_LE) ? bitswap_32(code_prefix) >> (32 - table_nb_bits) : code_prefix; table[j][1] = -subtable_bits; ff_dlog(NULL, "%4x: n=%d (subtable)\n", j, codes[i].bits + table_nb_bits); @@ -319,7 +319,7 @@ int ff_init_vlc_sparse(VLC *vlc_arg, int nb_bits, int nb_codes, av_free(buf); \ return AVERROR(EINVAL); \ } \ - if (flags & INIT_VLC_LE) \ + if (flags & INIT_VLC_INPUT_LE) \ buf[j].code = bitswap_32(buf[j].code); \ else \ buf[j].code <<= 32 - buf[j].bits; \ diff --git a/libavcodec/vlc.h b/libavcodec/vlc.h index 42ccddf3fc..22d3e33485 100644 --- a/libavcodec/vlc.h +++ b/libavcodec/vlc.h @@ -51,26 +51,35 @@ int ff_init_vlc_sparse(VLC *vlc, int nb_bits, int nb_codes, int flags); void ff_free_vlc(VLC *vlc); -#define INIT_VLC_LE 2 +/* If INIT_VLC_INPUT_LE is set, the LSB bit of the codes used to + * initialize the VLC table is the first bit to be read. */ +#define INIT_VLC_INPUT_LE 2 +/* If set the VLC is intended for a little endian bitstream reader. */ +#define INIT_VLC_OUTPUT_LE 8 +#define INIT_VLC_LE (INIT_VLC_INPUT_LE | INIT_VLC_OUTPUT_LE) #define INIT_VLC_USE_NEW_STATIC 4 -#define INIT_VLC_SPARSE_STATIC(vlc, bits, a, b, c, d, e, f, g, h, i, j, static_size) \ +#define INIT_CUSTOM_VLC_SPARSE_STATIC(vlc, bits, a, b, c, d, e, f, g, \ + h, i, j, flags, static_size) \ do { \ static VLC_TYPE table[static_size][2]; \ (vlc)->table = table; \ (vlc)->table_allocated = static_size; \ ff_init_vlc_sparse(vlc, bits, a, b, c, d, e, f, g, h, i, j, \ - INIT_VLC_USE_NEW_STATIC); \ + flags | INIT_VLC_USE_NEW_STATIC); \ } while (0) +#define INIT_VLC_SPARSE_STATIC(vlc, bits, a, b, c, d, e, f, g, h, i, j, static_size) \ + INIT_CUSTOM_VLC_SPARSE_STATIC(vlc, bits, a, b, c, d, e, f, g, \ + h, i, j, 0, static_size) + #define INIT_LE_VLC_SPARSE_STATIC(vlc, bits, a, b, c, d, e, f, g, h, i, j, static_size) \ - do { \ - static VLC_TYPE table[static_size][2]; \ - (vlc)->table = table; \ - (vlc)->table_allocated = static_size; \ - ff_init_vlc_sparse(vlc, bits, a, b, c, d, e, f, g, h, i, j, \ - INIT_VLC_USE_NEW_STATIC | INIT_VLC_LE); \ - } while (0) + INIT_CUSTOM_VLC_SPARSE_STATIC(vlc, bits, a, b, c, d, e, f, g, \ + h, i, j, INIT_VLC_LE, static_size) + +#define INIT_CUSTOM_VLC_STATIC(vlc, bits, a, b, c, d, e, f, g, flags, static_size) \ + INIT_CUSTOM_VLC_SPARSE_STATIC(vlc, bits, a, b, c, d, e, f, g, \ + NULL, 0, 0, flags, static_size) #define INIT_VLC_STATIC(vlc, bits, a, b, c, d, e, f, g, static_size) \ INIT_VLC_SPARSE_STATIC(vlc, bits, a, b, c, d, e, f, g, NULL, 0, 0, static_size) |