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author | wm4 <wm4@nowhere> | 2017-11-05 16:36:18 +0100 |
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committer | wm4 <wm4@nowhere> | 2017-11-05 18:13:34 +0100 |
commit | 9e1fbffc37779c8f491d3aa8e319ab233e5ab0da (patch) | |
tree | 894c25cc6443805d3453c3a4788ed4ab1ee0bedc /demux/packet.c | |
parent | 8aa1db3b175d29201f55648849b4f2ddc15f8ea1 (diff) | |
download | mpv-9e1fbffc37779c8f491d3aa8e319ab233e5ab0da.tar.bz2 mpv-9e1fbffc37779c8f491d3aa8e319ab233e5ab0da.tar.xz |
demux_mkv: rewrite packet reading to avoid 1 memcpy()
This directly reads individual mkv sub-packets (block laces) into a
dedicated AVBufferRefs, which can be directly used for creating packets
without a additional copy of the packet data. This also means we switch
parsing of block header fields and lacing metadata to read directly from
the stream, instead of a memory buffer.
This could have been much easier if libavcodec didn't require padding
the packet data with zero bytes. We could just have each packet
reference a slice of the block data. But as it is, the only way to get
padding without a copy is to read the laces into individually allocated
(and padded) memory block, which required a larger rewrite.
This probably makes recovering from broken mkv files slightly worse if
the transport is unseekable. We just read, and then check if we've
overread. But I think that shouldn't be a real concern.
No actual measureable performance change. Potential for some
regressions, as this is quite intrusive, and touches weird obscure shit
like mkv lacing. Still keeping it because I like how it removes some
redundant EBML parsing functions.
Diffstat (limited to 'demux/packet.c')
-rw-r--r-- | demux/packet.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/demux/packet.c b/demux/packet.c index 156222737c..84fda8c736 100644 --- a/demux/packet.c +++ b/demux/packet.c @@ -75,6 +75,17 @@ struct demux_packet *new_demux_packet_from_avpacket(struct AVPacket *avpkt) return dp; } +// (buf must include proper padding) +struct demux_packet *new_demux_packet_from_buf(struct AVBufferRef *buf) +{ + AVPacket pkt = { + .size = buf->size, + .data = buf->data, + .buf = buf, + }; + return new_demux_packet_from_avpacket(&pkt); +} + // Input data doesn't need to be padded. struct demux_packet *new_demux_packet_from(void *data, size_t len) { |