* commit 'a8cbe5a0ccebf60a8a8b0aba5d5716dd54c1595c':
h264_ps: export actual height in MBs as SPS.mb_height
Merged-by: Hendrik Leppkes <h.leppkes@gmail.com>
* commit '99cf943339a2e5171863c48cd1a73dd43dc243e1':
d3d11va: don't keep the context lock while waiting for a frame
Merged-by: Hendrik Leppkes <h.leppkes@gmail.com>
* commit '2866d108c9e9da7baf53ff57a51d470691049a57':
vp8dsp: Remove the comment saying that the height is equal to the width
Merged-by: Hendrik Leppkes <h.leppkes@gmail.com>
* commit '8c816c0c9b12fdefd9046415e97df299880bc9b8':
checkasm/arm: align the clobber check data properly for ldrd
Merged-by: Hendrik Leppkes <h.leppkes@gmail.com>
* commit 'ec32574209f36467ef0d22c21a7e811ba98c15b6':
checkasm: vp8: mc: test unequal width/height for partitions
Merged-by: Hendrik Leppkes <h.leppkes@gmail.com>
* commit 'fc5cdc0d5372f5103c71d5dede296734fe71ead2':
doc: escape left brace in texi2pod.pl regex
This commit is a noop, see e43ea1cbb2
Merged-by: Hendrik Leppkes <h.leppkes@gmail.com>
* commit 'd825b1a5306576dcd0553b7d0d24a3a46ad92864':
libopenh264: Support building with the 1.6 release
This commit is a noop, see 293676c476
Merged-by: Hendrik Leppkes <h.leppkes@gmail.com>
* commit '4f7723cb3b913c577842a5bb088c804ddacac8df':
movenc: Add an option for skipping writing the mfra/tfra/mfro trailer
Merged-by: Hendrik Leppkes <h.leppkes@gmail.com>
A number of new pix_fmts* have been added to AviSynth+:
16-bit packed RGB and RGBA
10-, 12-, 14, and 16-bit YUV 4:2:0, 4:2:2, and 4:4:4
8-, 10-, 12-, 14-, and 16-bit Planar RGB
8-, 10-, 12-, 14-, and 16-bit Planar YUVA and Planar RGBA
10-, 12-, 14-, and 16-bit GRAY variants
32-bit floating point Planar YUV(A), Planar RGB(A), and GRAY
*some of which are not currently available pix_fmts here and were
not added to the demuxer due to this
Signed-off-by: Diego Biurrun <diego@biurrun.de>
Stream timebase should be set using avpriv_set_pts_info, otherwise
avctx->pkt_timebase is not correct, leading to A/V desync.
Signed-off-by: Marton Balint <cus@passwd.hu>
Reviewed-by: Stephen Hutchinson <qyot27@gmail.com>
Signed-off-by: Diego Biurrun <diego@biurrun.de>
uint32 need 4 bytes not 1.
Fix decoding when there is half/float and uint32 channel.
This fixes crashes due to pointer corruption caused by invalid writes.
The problem was introduced in commit
03152e74df.
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
channel_index can be -1.
This problem was introduced in commit
2dd7b46132.
Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
They are not valid and can cause problems/crashes for API users.
Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
This fixes NULL pointer dereferencing for formats, where frame->data[1]
is not allocated.
The problem was introduced in commit
257fbc3af4.
Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
This prevented the code from correctly exporting the rotation matrix
which caused a few samples to be displayed wrong.
Introduced in ecd2ec69ce.
Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>
Fixes building with --disable-everything --enable-shared --enable-dxva2
The hwcontext DXVA2 implementation in avutil needs this library now, instead
of just the ffmpeg program.
The dc-only mode is already checked to work correctly above, but this
allows benchmarking this mode for performance tuning, and allows making
sure that it actually is correctly hooked up.
Signed-off-by: Martin Storsjö <martin@martin.st>
The latter is 1 cycle faster on a cortex-53 and since the operands are
bytewise (or larger) bitmask (impossible to overflow to zero) both are
equivalent.
Since aarch64 has enough free general purpose registers use them to
branch to the appropiate storage code. 1-2 cycles faster for the
functions using loop_filter 8/16, ... on a cortex-a53. Mixed results
(up to 2 cycles faster/slower) on a cortex-a57.
In the latest git commits of libilbc developers removed WebRtc_xxx typedefs.
This commit uses int types instead. It's safe to apply also for previous
versions since WebRtc_Word16 was always a typedef of int16_t and
WebRtc_UWord16 a typedef of uint16_t.
Reviewed-by: Timothy Gu <timothygu99@gmail.com>
Signed-off-by: Diego Biurrun <diego@biurrun.de>
This fixes a heap-buffer-overflow detected by AddressSanitizer.
Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
This work is sponsored by, and copyright, Google.
These are ported from the ARM version; thanks to the larger
amount of registers available, we can do the loop filters with
16 pixels at a time. The implementation is fully templated, with
a single macro which can generate versions for both 8 and
16 pixels wide, for both 4, 8 and 16 pixels loop filters
(and the 4/8 mixed versions as well).
For the 8 pixel wide versions, it is pretty close in speed (the
v_4_8 and v_8_8 filters are the best examples of this; the h_4_8
and h_8_8 filters seem to get some gain in the load/transpose/store
part). For the 16 pixels wide ones, we get a speedup of around
1.2-1.4x compared to the 32 bit version.
Examples of runtimes vs the 32 bit version, on a Cortex A53:
ARM AArch64
vp9_loop_filter_h_4_8_neon: 144.0 127.2
vp9_loop_filter_h_8_8_neon: 207.0 182.5
vp9_loop_filter_h_16_8_neon: 415.0 328.7
vp9_loop_filter_h_16_16_neon: 672.0 558.6
vp9_loop_filter_mix2_h_44_16_neon: 302.0 203.5
vp9_loop_filter_mix2_h_48_16_neon: 365.0 305.2
vp9_loop_filter_mix2_h_84_16_neon: 365.0 305.2
vp9_loop_filter_mix2_h_88_16_neon: 376.0 305.2
vp9_loop_filter_mix2_v_44_16_neon: 193.2 128.2
vp9_loop_filter_mix2_v_48_16_neon: 246.7 218.4
vp9_loop_filter_mix2_v_84_16_neon: 248.0 218.5
vp9_loop_filter_mix2_v_88_16_neon: 302.0 218.2
vp9_loop_filter_v_4_8_neon: 89.0 88.7
vp9_loop_filter_v_8_8_neon: 141.0 137.7
vp9_loop_filter_v_16_8_neon: 295.0 272.7
vp9_loop_filter_v_16_16_neon: 546.0 453.7
The speedup vs C code in checkasm tests is around 2-7x, which is
pretty much the same as for the 32 bit version. Even if these functions
are faster than their 32 bit equivalent, the C version that we compare
to also became around 1.3-1.7x faster than the C version in 32 bit.
Based on START_TIMER/STOP_TIMER wrapping around a few individual
functions, the speedup vs C code is around 4-5x.
Examples of runtimes vs C on a Cortex A57 (for a slightly older version
of the patch):
A57 gcc-5.3 neon
loop_filter_h_4_8_neon: 256.6 93.4
loop_filter_h_8_8_neon: 307.3 139.1
loop_filter_h_16_8_neon: 340.1 254.1
loop_filter_h_16_16_neon: 827.0 407.9
loop_filter_mix2_h_44_16_neon: 524.5 155.4
loop_filter_mix2_h_48_16_neon: 644.5 173.3
loop_filter_mix2_h_84_16_neon: 630.5 222.0
loop_filter_mix2_h_88_16_neon: 697.3 222.0
loop_filter_mix2_v_44_16_neon: 598.5 100.6
loop_filter_mix2_v_48_16_neon: 651.5 127.0
loop_filter_mix2_v_84_16_neon: 591.5 167.1
loop_filter_mix2_v_88_16_neon: 855.1 166.7
loop_filter_v_4_8_neon: 271.7 65.3
loop_filter_v_8_8_neon: 312.5 106.9
loop_filter_v_16_8_neon: 473.3 206.5
loop_filter_v_16_16_neon: 976.1 327.8
The speed-up compared to the C functions is 2.5 to 6 and the cortex-a57
is again 30-50% faster than the cortex-a53.
This is an adapted cherry-pick from libav commits
9d2afd1eb8 and
31756abe29.
Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>
This work is sponsored by, and copyright, Google.
These are ported from the ARM version; thanks to the larger
amount of registers available, we can do the 16x16 and 32x32
transforms in slices 8 pixels wide instead of 4. This gives
a speedup of around 1.4x compared to the 32 bit version.
The fact that aarch64 doesn't have the same d/q register
aliasing makes some of the macros quite a bit simpler as well.
Examples of runtimes vs the 32 bit version, on a Cortex A53:
ARM AArch64
vp9_inv_adst_adst_4x4_add_neon: 90.0 87.7
vp9_inv_adst_adst_8x8_add_neon: 400.0 354.7
vp9_inv_adst_adst_16x16_add_neon: 2526.5 1827.2
vp9_inv_dct_dct_4x4_add_neon: 74.0 72.7
vp9_inv_dct_dct_8x8_add_neon: 271.0 256.7
vp9_inv_dct_dct_16x16_add_neon: 1960.7 1372.7
vp9_inv_dct_dct_32x32_add_neon: 11988.9 8088.3
vp9_inv_wht_wht_4x4_add_neon: 63.0 57.7
The speedup vs C code (2-4x) is smaller than in the 32 bit case,
mostly because the C code ends up significantly faster (around
1.6x faster, with GCC 5.4) when built for aarch64.
Examples of runtimes vs C on a Cortex A57 (for a slightly older version
of the patch):
A57 gcc-5.3 neon
vp9_inv_adst_adst_4x4_add_neon: 152.2 60.0
vp9_inv_adst_adst_8x8_add_neon: 948.2 288.0
vp9_inv_adst_adst_16x16_add_neon: 4830.4 1380.5
vp9_inv_dct_dct_4x4_add_neon: 153.0 58.6
vp9_inv_dct_dct_8x8_add_neon: 789.2 180.2
vp9_inv_dct_dct_16x16_add_neon: 3639.6 917.1
vp9_inv_dct_dct_32x32_add_neon: 20462.1 4985.0
vp9_inv_wht_wht_4x4_add_neon: 91.0 49.8
The asm is around factor 3-4 faster than C on the cortex-a57 and the asm
is around 30-50% faster on the a57 compared to the a53.
This is an adapted cherry-pick from libav commit
3c9546dfaf.
Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>
This work is sponsored by, and copyright, Google.
These are ported from the ARM version; it is essentially a 1:1
port with no extra added features, but with some hand tuning
(especially for the plain copy/avg functions). The ARM version
isn't very register starved to begin with, so there's not much
to be gained from having more spare registers here - we only
avoid having to clobber callee-saved registers.
Examples of runtimes vs the 32 bit version, on a Cortex A53:
ARM AArch64
vp9_avg4_neon: 27.2 23.7
vp9_avg8_neon: 56.5 54.7
vp9_avg16_neon: 169.9 167.4
vp9_avg32_neon: 585.8 585.2
vp9_avg64_neon: 2460.3 2294.7
vp9_avg_8tap_smooth_4h_neon: 132.7 125.2
vp9_avg_8tap_smooth_4hv_neon: 478.8 442.0
vp9_avg_8tap_smooth_4v_neon: 126.0 93.7
vp9_avg_8tap_smooth_8h_neon: 241.7 234.2
vp9_avg_8tap_smooth_8hv_neon: 690.9 646.5
vp9_avg_8tap_smooth_8v_neon: 245.0 205.5
vp9_avg_8tap_smooth_64h_neon: 11273.2 11280.1
vp9_avg_8tap_smooth_64hv_neon: 22980.6 22184.1
vp9_avg_8tap_smooth_64v_neon: 11549.7 10781.1
vp9_put4_neon: 18.0 17.2
vp9_put8_neon: 40.2 37.7
vp9_put16_neon: 97.4 99.5
vp9_put32_neon/armv8: 346.0 307.4
vp9_put64_neon/armv8: 1319.0 1107.5
vp9_put_8tap_smooth_4h_neon: 126.7 118.2
vp9_put_8tap_smooth_4hv_neon: 465.7 434.0
vp9_put_8tap_smooth_4v_neon: 113.0 86.5
vp9_put_8tap_smooth_8h_neon: 229.7 221.6
vp9_put_8tap_smooth_8hv_neon: 658.9 621.3
vp9_put_8tap_smooth_8v_neon: 215.0 187.5
vp9_put_8tap_smooth_64h_neon: 10636.7 10627.8
vp9_put_8tap_smooth_64hv_neon: 21076.8 21026.9
vp9_put_8tap_smooth_64v_neon: 9635.0 9632.4
These are generally about as fast as the corresponding ARM
routines on the same CPU (at least on the A53), in most cases
marginally faster.
The speedup vs C code is pretty much the same as for the 32 bit
case; on the A53 it's around 6-13x for ther larger 8tap filters.
The exact speedup varies a little, since the C versions generally
don't end up exactly as slow/fast as on 32 bit.
This is an adapted cherry-pick from libav commit
383d96aa22.
Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>
With apple tools, the linker fails with errors like these, if the
offset is negative:
ld: in section __TEXT,__text reloc 8: symbol index out of range for architecture arm64
This is cherry-picked from libav commit
c44a8a3eab.
Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>
This work is sponsored by, and copyright, Google.
The implementation tries to have smart handling of cases
where no pixels need the full filtering for the 8/16 width
filters, skipping both calculation and writeback of the
unmodified pixels in those cases. The actual effect of this
is hard to test with checkasm though, since it tests the
full filtering, and the benefit depends on how many filtered
blocks use the shortcut.
Examples of relative speedup compared to the C version, from checkasm:
Cortex A7 A8 A9 A53
vp9_loop_filter_h_4_8_neon: 2.72 2.68 1.78 3.15
vp9_loop_filter_h_8_8_neon: 2.36 2.38 1.70 2.91
vp9_loop_filter_h_16_8_neon: 1.80 1.89 1.45 2.01
vp9_loop_filter_h_16_16_neon: 2.81 2.78 2.18 3.16
vp9_loop_filter_mix2_h_44_16_neon: 2.65 2.67 1.93 3.05
vp9_loop_filter_mix2_h_48_16_neon: 2.46 2.38 1.81 2.85
vp9_loop_filter_mix2_h_84_16_neon: 2.50 2.41 1.73 2.85
vp9_loop_filter_mix2_h_88_16_neon: 2.77 2.66 1.96 3.23
vp9_loop_filter_mix2_v_44_16_neon: 4.28 4.46 3.22 5.70
vp9_loop_filter_mix2_v_48_16_neon: 3.92 4.00 3.03 5.19
vp9_loop_filter_mix2_v_84_16_neon: 3.97 4.31 2.98 5.33
vp9_loop_filter_mix2_v_88_16_neon: 3.91 4.19 3.06 5.18
vp9_loop_filter_v_4_8_neon: 4.53 4.47 3.31 6.05
vp9_loop_filter_v_8_8_neon: 3.58 3.99 2.92 5.17
vp9_loop_filter_v_16_8_neon: 3.40 3.50 2.81 4.68
vp9_loop_filter_v_16_16_neon: 4.66 4.41 3.74 6.02
The speedup vs C code is around 2-6x. The numbers are quite
inconclusive though, since the checkasm test runs multiple filterings
on top of each other, so later rounds might end up with different
codepaths (different decisions on which filter to apply, based
on input pixel differences). Disabling the early-exit in the asm
doesn't give a fair comparison either though, since the C code
only does the necessary calcuations for each row.
Based on START_TIMER/STOP_TIMER wrapping around a few individual
functions, the speedup vs C code is around 4-9x.
This is pretty similar in runtime to the corresponding routines
in libvpx. (This is comparing vpx_lpf_vertical_16_neon,
vpx_lpf_horizontal_edge_8_neon and vpx_lpf_horizontal_edge_16_neon
to vp9_loop_filter_h_16_8_neon, vp9_loop_filter_v_16_8_neon
and vp9_loop_filter_v_16_16_neon - note that the naming of horizonal
and vertical is flipped between the libraries.)
In order to have stable, comparable numbers, the early exits in both
asm versions were disabled, forcing the full filtering codepath.
Cortex A7 A8 A9 A53
vp9_loop_filter_h_16_8_neon: 597.2 472.0 482.4 415.0
libvpx vpx_lpf_vertical_16_neon: 626.0 464.5 470.7 445.0
vp9_loop_filter_v_16_8_neon: 500.2 422.5 429.7 295.0
libvpx vpx_lpf_horizontal_edge_8_neon: 586.5 414.5 415.6 383.2
vp9_loop_filter_v_16_16_neon: 905.0 784.7 791.5 546.0
libvpx vpx_lpf_horizontal_edge_16_neon: 1060.2 751.7 743.5 685.2
Our version is consistently faster on on A7 and A53, marginally slower on
A8, and sometimes faster, sometimes slower on A9 (marginally slower in all
three tests in this particular test run).
This is an adapted cherry-pick from libav commit
dd299a2d6d.
Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>
This work is sponsored by, and copyright, Google.
For the transforms up to 8x8, we can fit all the data (including
temporaries) in registers and just do a straightforward transform
of all the data. For 16x16, we do a transform of 4x16 pixels in
4 slices, using a temporary buffer. For 32x32, we transform 4x32
pixels at a time, in two steps of 4x16 pixels each.
Examples of relative speedup compared to the C version, from checkasm:
Cortex A7 A8 A9 A53
vp9_inv_adst_adst_4x4_add_neon: 3.39 5.83 4.17 4.01
vp9_inv_adst_adst_8x8_add_neon: 3.79 4.86 4.23 3.98
vp9_inv_adst_adst_16x16_add_neon: 3.33 4.36 4.11 4.16
vp9_inv_dct_dct_4x4_add_neon: 4.06 6.16 4.59 4.46
vp9_inv_dct_dct_8x8_add_neon: 4.61 6.01 4.98 4.86
vp9_inv_dct_dct_16x16_add_neon: 3.35 3.44 3.36 3.79
vp9_inv_dct_dct_32x32_add_neon: 3.89 3.50 3.79 4.42
vp9_inv_wht_wht_4x4_add_neon: 3.22 5.13 3.53 3.77
Thus, the speedup vs C code is around 3-6x.
This is mostly marginally faster than the corresponding routines
in libvpx on most cores, tested with their 32x32 idct (compared to
vpx_idct32x32_1024_add_neon). These numbers are slightly in libvpx's
favour since their version doesn't clear the input buffer like ours
do (although the effect of that on the total runtime probably is
negligible.)
Cortex A7 A8 A9 A53
vp9_inv_dct_dct_32x32_add_neon: 18436.8 16874.1 14235.1 11988.9
libvpx vpx_idct32x32_1024_add_neon 20789.0 13344.3 15049.9 13030.5
Only on the Cortex A8, the libvpx function is faster. On the other cores,
ours is slightly faster even though ours has got source block clearing
integrated.
This is an adapted cherry-pick from libav commits
a67ae67083 and
52d196fb30.
Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>
This work is sponsored by, and copyright, Google.
The filter coefficients are signed values, where the product of the
multiplication with one individual filter coefficient doesn't
overflow a 16 bit signed value (the largest filter coefficient is
127). But when the products are accumulated, the resulting sum can
overflow the 16 bit signed range. Instead of accumulating in 32 bit,
we accumulate the largest product (either index 3 or 4) last with a
saturated addition.
(The VP8 MC asm does something similar, but slightly simpler, by
accumulating each half of the filter separately. In the VP9 MC
filters, each half of the filter can also overflow though, so the
largest component has to be handled individually.)
Examples of relative speedup compared to the C version, from checkasm:
Cortex A7 A8 A9 A53
vp9_avg4_neon: 1.71 1.15 1.42 1.49
vp9_avg8_neon: 2.51 3.63 3.14 2.58
vp9_avg16_neon: 2.95 6.76 3.01 2.84
vp9_avg32_neon: 3.29 6.64 2.85 3.00
vp9_avg64_neon: 3.47 6.67 3.14 2.80
vp9_avg_8tap_smooth_4h_neon: 3.22 4.73 2.76 4.67
vp9_avg_8tap_smooth_4hv_neon: 3.67 4.76 3.28 4.71
vp9_avg_8tap_smooth_4v_neon: 5.52 7.60 4.60 6.31
vp9_avg_8tap_smooth_8h_neon: 6.22 9.04 5.12 9.32
vp9_avg_8tap_smooth_8hv_neon: 6.38 8.21 5.72 8.17
vp9_avg_8tap_smooth_8v_neon: 9.22 12.66 8.15 11.10
vp9_avg_8tap_smooth_64h_neon: 7.02 10.23 5.54 11.58
vp9_avg_8tap_smooth_64hv_neon: 6.76 9.46 5.93 9.40
vp9_avg_8tap_smooth_64v_neon: 10.76 14.13 9.46 13.37
vp9_put4_neon: 1.11 1.47 1.00 1.21
vp9_put8_neon: 1.23 2.17 1.94 1.48
vp9_put16_neon: 1.63 4.02 1.73 1.97
vp9_put32_neon: 1.56 4.92 2.00 1.96
vp9_put64_neon: 2.10 5.28 2.03 2.35
vp9_put_8tap_smooth_4h_neon: 3.11 4.35 2.63 4.35
vp9_put_8tap_smooth_4hv_neon: 3.67 4.69 3.25 4.71
vp9_put_8tap_smooth_4v_neon: 5.45 7.27 4.49 6.52
vp9_put_8tap_smooth_8h_neon: 5.97 8.18 4.81 8.56
vp9_put_8tap_smooth_8hv_neon: 6.39 7.90 5.64 8.15
vp9_put_8tap_smooth_8v_neon: 9.03 11.84 8.07 11.51
vp9_put_8tap_smooth_64h_neon: 6.78 9.48 4.88 10.89
vp9_put_8tap_smooth_64hv_neon: 6.99 8.87 5.94 9.56
vp9_put_8tap_smooth_64v_neon: 10.69 13.30 9.43 14.34
For the larger 8tap filters, the speedup vs C code is around 5-14x.
This is significantly faster than libvpx's implementation of the same
functions, at least when comparing the put_8tap_smooth_64 functions
(compared to vpx_convolve8_horiz_neon and vpx_convolve8_vert_neon from
libvpx).
Absolute runtimes from checkasm:
Cortex A7 A8 A9 A53
vp9_put_8tap_smooth_64h_neon: 20150.3 14489.4 19733.6 10863.7
libvpx vpx_convolve8_horiz_neon: 52623.3 19736.4 21907.7 25027.7
vp9_put_8tap_smooth_64v_neon: 14455.0 12303.9 13746.4 9628.9
libvpx vpx_convolve8_vert_neon: 42090.0 17706.2 17659.9 16941.2
Thus, on the A9, the horizontal filter is only marginally faster than
libvpx, while our version is significantly faster on the other cores,
and the vertical filter is significantly faster on all cores. The
difference is especially large on the A7.
The libvpx implementation does the accumulation in 32 bit, which
probably explains most of the differences.
This is an adapted cherry-pick from libav commits
ffbd1d2b0002576ef0d976a41ff959c635373fdc,
392caa65df3efa8b2d48a80f08a6af4892c61c08,
557c1675cf and
11623217e3.
Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>
We reset .Lpic_gp to zero at the start of each function, which means
that the logic within movrelx for clearing gp when necessary will
be missed.
This fixes using movrelx in different functions with a different
helper register.
This is cherry-picked from libav commit
824e8c2840.
Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>
Make them aligned, to allow efficient access to them from simd.
This is an adapted cherry-pick from libav commit
a4cfcddcb0.
Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>
Hendrik Leppkes
Carl Eugen Hoyos
Michael Niedermayer
Diego Biurrun
Stephen Hutchinson
Marton Balint
Martin Vignali
Andreas Cadhalpun
Vittorio Giovara
kieranjol
Martin Storsjö
Janne Grunau
Gianluigi Tiesi
Thierry Foucu