FFmpeg/libavformat/av1.h
Andreas Rheinhardt a3e43e0cf3 avformat/av1: Avoid allocation + copying when filtering OBUs
Certain types of OBUs are stripped away before muxing into Matroska and
ISOBMFF; there are two functions to do this: One that outputs by
directly writing in an AVIOContext and one that returns a freshly
allocated buffer with the units not stripped away copied into it.

The latter option is bad for performance, especially when the input
does already not contain any of the units intended to be stripped away
(this covers typical remuxing scenarios). Therefore this commit changes
this by avoiding allocating and copying when possible; it is possible if
the OBUs to be retained are consecutively in the input buffer (without
an OBU to be discarded between them). In this case, the caller receives
the offset as well as the length of the part of the buffer that contains
the units to be kept. This also avoids copying when e.g. the only unit
to be discarded is a temporal delimiter at the front.

For a 22.7mb/s file with average framesize 113 kB this improved the time
for the calls to ff_av1_filter_obus_buf() when writing Matroska from
313319 decicycles to 2368 decicycles; for another file with 1.5mb/s
(average framesize 7.3 kB) it improved from 34539 decicycles to 1922
decicyles. For these files the only units that needed to be stripped
away were temporal unit delimiters at the front.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
Signed-off-by: James Almer <jamrial@gmail.com>
2020-01-26 12:41:32 -03:00

103 lines
3.7 KiB
C

/*
* AV1 helper functions for muxers
*
* This file is part of FFmpeg.
*
* FFmpeg 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.
*
* FFmpeg 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 FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef AVFORMAT_AV1_H
#define AVFORMAT_AV1_H
#include <stdint.h>
#include "avio.h"
typedef struct AV1SequenceParameters {
uint8_t profile;
uint8_t level;
uint8_t tier;
uint8_t bitdepth;
uint8_t monochrome;
uint8_t chroma_subsampling_x;
uint8_t chroma_subsampling_y;
uint8_t chroma_sample_position;
uint8_t color_description_present_flag;
uint8_t color_primaries;
uint8_t transfer_characteristics;
uint8_t matrix_coefficients;
uint8_t color_range;
} AV1SequenceParameters;
/**
* Filter out AV1 OBUs not meant to be present in ISOBMFF sample data and write
* the resulting bitstream to the provided AVIOContext.
*
* @param pb pointer to the AVIOContext where the filtered bitstream shall be
* written
* @param buf input data buffer
* @param size size of the input data buffer
*
* @return the amount of bytes written in case of success, a negative AVERROR
* code in case of failure
*/
int ff_av1_filter_obus(AVIOContext *pb, const uint8_t *buf, int size);
/**
* Filter out AV1 OBUs not meant to be present in ISOBMFF sample data and return
* the result in a data buffer, avoiding allocations and copies if possible.
*
* @param in input data buffer
* @param out pointer to pointer for the returned buffer. In case of success,
* it is independently allocated if and only if `*out` differs from in.
* @param size size of the input data buffer. The size of the resulting output
* data buffer will be written here
* @param offset offset of the returned data inside `*out`: It runs from
* `*out + offset` (inclusive) to `*out + offset + size`
* (exclusive); is zero if `*out` is independently allocated.
*
* @return 0 in case of success, a negative AVERROR code in case of failure.
* On failure, *out and *size are unchanged
* @note *out will be treated as unintialized on input and will not be freed.
*/
int ff_av1_filter_obus_buf(const uint8_t *in, uint8_t **out,
int *size, int *offset);
/**
* Parses a Sequence Header from the the provided buffer.
*
* @param seq pointer to the AV1SequenceParameters where the parsed values will
* be written
* @param buf input data buffer
* @param size size in bytes of the input data buffer
*
* @return >= 0 in case of success, a negative AVERROR code in case of failure
*/
int ff_av1_parse_seq_header(AV1SequenceParameters *seq, const uint8_t *buf, int size);
/**
* Writes AV1 extradata (Sequence Header and Metadata OBUs) to the provided
* AVIOContext.
*
* @param pb pointer to the AVIOContext where the av1C box shall be written
* @param buf input data buffer
* @param size size in bytes of the input data buffer
*
* @return >= 0 in case of success, a negative AVERROR code in case of failure
*/
int ff_isom_write_av1c(AVIOContext *pb, const uint8_t *buf, int size);
#endif /* AVFORMAT_AV1_H */