This adds tons of code for no other benefit than making VideoToolbox
support conform with the new hwaccel API (using hw_device_ctx and
hw_frames_ctx).
Since VideoToolbox decoding does not actually require the user to
allocate frames, the new code does mostly nothing.
One benefit is that ffmpeg_videotoolbox.c can be dropped once generic
hwaccel support for ffmpeg.c is merged from Libav.
Does not consider VDA or VideoToolbox encoding.
Fun fact: the frame transfer functions are copied from vaapi, as the
mapping makes copying generic boilerplate. Mapping itself is not
exported by the VT code, because I don't know how to test.
The way videotoolbox hooks in as a hwaccel is pretty hacky. The VT decode
API is not invoked until end_frame(), so alloc_frame() returns a dummy
frame with a 1-byte buffer. When end_frame() is eventually called, the
dummy buffer is replaced with the actual decoded data from
VTDecompressionSessionDecodeFrame().
When the VT decoder fails, the frame returned to the h264 decoder from
alloc_frame() remains invalid and should not be used. Before
9747219958, it was accidentally being
returned all the way up to the API user. After that commit, the dummy
frame was unref'd so the user received an error.
However, since that commit, VT hwaccel failures started causing random
segfaults in the h264 decoder. This happened more often on iOS where the
VT implementation is more likely to throw errors on bitstream anomolies.
A recent report of this issue can be see in
http://ffmpeg.org/pipermail/libav-user/2016-November/009831.html
The issue here is that the dummy frame is still referenced internally by the
h264 decoder, as part of the reflist and cur_pic_ptr. Deallocating the
frame causes assertions like this one to trip later on during decoding:
Assertion h->cur_pic_ptr->f->buf[0] failed at src/libavcodec/h264_slice.c:1340
With this commit, we leave the dummy 1-byte frame intact, but avoid returning it
to the user.
This reverts commit 9747219958.
Signed-off-by: wm4 <nfxjfg@googlemail.com>
If AVVideotoolboxContext.cv_pix_fmt_type is set to 0, don't set the
kCVPixelBufferPixelFormatTypeKey value on the VT decoder.
This makes VT output its native format, which can be much faster on
some hardware iterations (if the native format does not match with
the requested format, it will be converted, which is slow).
The default is still forcing nv12.
"When you are done with a decompression session you created, call
VTDecompressionSessionInvalidate to tear it down and then CFRelease to
release your object reference."
If videotoolbox_common_end_frame failed, then the AVFrame was returned
to the API user with the dummy buffer (in AVFrame.buf[0]) still set, and
the decode call indicating success.
These "half-set" AVFrames with dummy buffer are a videotoolbox specific
hack, because the decoder requires an allocated AVFrame for its internal
logic. Videotoolbox on the other hand allocates its frame itself
internally, and outputs it only on end_frame. At this point, the dummy
buffer is replaced with the real frame (unless decoding fails).
This affects Annex B streams (such as demuxed from .ts and others). It
also handles the format change in reinit-large_420_8-to-small_420_8.h264
correctly.
Instead of passing through the extradata, create it on the fly it from
the currently active SPS and PPS. Since reconstructing the PPS and SPS
NALs would be very complicated and verbose, we use the NALs as they
originally appeared in the bitstream.
The code for writing the extradata is somewhat derived from
libavformat/avc.c, but it's small and different enough that sharing it
is not really worth it.
VideoToolbox also implements a software decoder for h264, and will fallback to
using it if the file cannot be decoded on the GPU. In these cases though,
we want the hwaccel to fail so that we can use the libavcodec software decoder
instead of the Apple one.
Signed-off-by: wm4 <nfxjfg@googlemail.com>
pix_fmt was declared presumably to shorten the argument passed to the function.
However, it is currently not being used for such a purpose.
This patch simply removes it instead.
This fixes -Wunused-but-set-variable reported at e.g:
http://fate.ffmpeg.org/log.cgi?time=20150919194249&log=compile&slot=x86_64-darwin-gcc-4.9.
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
Reviewed-by: wm4 <nfxjfg@googlemail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
wm4
Aman Gupta
wang-bin
Matthieu Bouron
Dan Dennedy
Clément Bœsch
Rick Kern
Clément Bœsch
Stefano Pigozzi
Ganesh Ajjanagadde
Michael Niedermayer
Sebastien Zwickert