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mirror of https://github.com/mpv-player/mpv synced 2024-11-18 21:16:10 +01:00
mpv/demux/packet.h
wm4 9e1fbffc37 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.
2017-11-05 18:13:34 +01:00

67 lines
2.3 KiB
C

/*
* This file is part of mpv.
*
* mpv is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* mpv is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with mpv. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef MPLAYER_DEMUX_PACKET_H
#define MPLAYER_DEMUX_PACKET_H
#include <stdbool.h>
#include <stddef.h>
#include <inttypes.h>
// Holds one packet/frame/whatever
typedef struct demux_packet {
int len;
unsigned char *buffer;
double pts;
double dts;
double duration;
bool keyframe;
int64_t pos; // position in source file byte stream
int stream; // source stream index
// segmentation (ordered chapters, EDL)
bool segmented;
struct mp_codec_params *codec; // set to non-NULL iff segmented is set
double start, end; // set to non-NOPTS iff segmented is set
// private
struct demux_packet *next;
struct AVPacket *avpacket; // keep the buffer allocation and sidedata
double kf_seek_pts; // demux.c internal: seek pts for keyframe range
} demux_packet_t;
struct AVBufferRef;
struct demux_packet *new_demux_packet(size_t len);
struct demux_packet *new_demux_packet_from_avpacket(struct AVPacket *avpkt);
struct demux_packet *new_demux_packet_from(void *data, size_t len);
struct demux_packet *new_demux_packet_from_buf(struct AVBufferRef *buf);
void demux_packet_shorten(struct demux_packet *dp, size_t len);
void free_demux_packet(struct demux_packet *dp);
struct demux_packet *demux_copy_packet(struct demux_packet *dp);
size_t demux_packet_estimate_total_size(struct demux_packet *dp);
void demux_packet_copy_attribs(struct demux_packet *dst, struct demux_packet *src);
int demux_packet_set_padding(struct demux_packet *dp, int start, int end);
int demux_packet_add_blockadditional(struct demux_packet *dp, uint64_t id,
void *data, size_t size);
#endif /* MPLAYER_DEMUX_PACKET_H */