From 9e1fbffc37779c8f491d3aa8e319ab233e5ab0da Mon Sep 17 00:00:00 2001 From: wm4 Date: Sun, 5 Nov 2017 16:36:18 +0100 Subject: 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. --- demux/ebml.h | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'demux/ebml.h') diff --git a/demux/ebml.h b/demux/ebml.h index 8b67ea7071..86a40092b6 100644 --- a/demux/ebml.h +++ b/demux/ebml.h @@ -80,9 +80,8 @@ struct ebml_parse_ctx { bool ebml_is_mkv_level1_id(uint32_t id); uint32_t ebml_read_id (stream_t *s); -uint64_t ebml_read_vlen_uint (bstr *buffer); -int64_t ebml_read_vlen_int (bstr *buffer); uint64_t ebml_read_length (stream_t *s); +int64_t ebml_read_signed_length(stream_t *s); uint64_t ebml_read_uint (stream_t *s); int64_t ebml_read_int (stream_t *s); int ebml_read_skip(struct mp_log *log, int64_t end, stream_t *s); -- cgit v1.2.3