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/*
* EVC format parser
*
* Copyright (C) 2021 Dawid Kozinski <d.kozinski@samsung.com>
*
* 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
*/
#include "parser.h"
#include "bytestream.h"
#include "evc.h"
#include "evc_parse.h"
/**
* Parse NAL units of found picture and decode some basic information.
*
* @param s codec parser context
* @param avctx codec context
* @param buf buffer with field/frame data
* @param buf_size size of the buffer
*/
static int parse_nal_units(AVCodecParserContext *s, AVCodecContext *avctx, const uint8_t *buf, int buf_size)
{
EVCParserContext *ctx = s->priv_data;
const uint8_t *data = buf;
int data_size = buf_size;
int bytes_read = 0;
int nalu_size = 0;
while (data_size > 0) {
// Buffer size is not enough for buffer to store NAL unit 4-bytes prefix (length)
if (data_size < EVC_NALU_LENGTH_PREFIX_SIZE)
return AVERROR_INVALIDDATA;
nalu_size = evc_read_nal_unit_length(data, data_size, avctx);
bytes_read += EVC_NALU_LENGTH_PREFIX_SIZE;
data += EVC_NALU_LENGTH_PREFIX_SIZE;
data_size -= EVC_NALU_LENGTH_PREFIX_SIZE;
if (data_size < nalu_size)
return AVERROR_INVALIDDATA;
if (ff_evc_parse_nal_unit(ctx, data, nalu_size, avctx) != 0) {
av_log(avctx, AV_LOG_ERROR, "Parsing of NAL unit failed\n");
return AVERROR_INVALIDDATA;
}
if(ctx->nalu_type == EVC_SPS_NUT) {
s->coded_width = ctx->coded_width;
s->coded_height = ctx->coded_height;
s->width = ctx->width;
s->height = ctx->height;
s->format = ctx->format;
avctx->framerate = ctx->framerate;
avctx->gop_size = ctx->gop_size;
avctx->delay = ctx->delay;
avctx->profile = ctx->profile;
} else if(ctx->nalu_type == EVC_NOIDR_NUT || ctx->nalu_type == EVC_IDR_NUT) {
s->pict_type = ctx->pict_type;
s->key_frame = ctx->key_frame;
s->output_picture_number = ctx->output_picture_number;
}
data += nalu_size;
data_size -= nalu_size;
}
return 0;
}
// Decoding nal units from evcC (EVCDecoderConfigurationRecord)
// @see @see ISO/IEC 14496-15:2021 Coding of audio-visual objects - Part 15: section 12.3.3.2
static int decode_extradata(EVCParserContext *ctx, const uint8_t *data, int size, void *logctx)
{
int ret = 0;
GetByteContext gb;
bytestream2_init(&gb, data, size);
if (!data || size <= 0)
return -1;
// extradata is encoded as evcC format.
if (data[0] == 1) {
int num_of_arrays; // indicates the number of arrays of NAL units of the indicated type(s)
int nalu_length_field_size; // indicates the length in bytes of the NALUnitLenght field in EVC video stream sample in the stream
// The value of this field shall be one of 0, 1, or 3 corresponding to a length encoded with 1, 2, or 4 bytes, respectively.
if (bytestream2_get_bytes_left(&gb) < 18) {
av_log(logctx, AV_LOG_ERROR, "evcC %d too short\n", size);
return AVERROR_INVALIDDATA;
}
bytestream2_skip(&gb, 16);
// @see ISO/IEC 14496-15:2021 Coding of audio-visual objects - Part 15: section 12.3.3.3
// LengthSizeMinusOne plus 1 indicates the length in bytes of the NALUnitLength field in a EVC video stream sample in the stream to which this configuration record applies. For example, a size of one byte is indicated with a value of 0.
// The value of this field shall be one of 0, 1, or 3 corresponding to a length encoded with 1, 2, or 4 bytes, respectively.
nalu_length_field_size = (bytestream2_get_byte(&gb) & 3) + 1;
if( nalu_length_field_size != 1 &&
nalu_length_field_size != 2 &&
nalu_length_field_size != 4 ) {
av_log(logctx, AV_LOG_ERROR, "The length in bytes of the NALUnitLenght field in a EVC video stream has unsupported value of %d\n", nalu_length_field_size);
return AVERROR_INVALIDDATA;
}
num_of_arrays = bytestream2_get_byte(&gb);
/* Decode nal units from evcC. */
for (int i = 0; i < num_of_arrays; i++) {
// @see ISO/IEC 14496-15:2021 Coding of audio-visual objects - Part 15: section 12.3.3.3
// NAL_unit_type indicates the type of the NAL units in the following array (which shall be all of that type);
// - it takes a value as defined in ISO/IEC 23094-1;
// - it is restricted to take one of the values indicating a SPS, PPS, APS, or SEI NAL unit.
int nal_unit_type = bytestream2_get_byte(&gb) & 0x3f;
int num_nalus = bytestream2_get_be16(&gb);
for (int j = 0; j < num_nalus; j++) {
int nal_unit_length = bytestream2_get_be16(&gb);
if (bytestream2_get_bytes_left(&gb) < nal_unit_length) {
av_log(logctx, AV_LOG_ERROR, "Invalid NAL unit size in extradata.\n");
return AVERROR_INVALIDDATA;
}
if( nal_unit_type == EVC_SPS_NUT ||
nal_unit_type == EVC_PPS_NUT ||
nal_unit_type == EVC_APS_NUT ||
nal_unit_type == EVC_SEI_NUT ) {
if (ff_evc_parse_nal_unit(ctx, gb.buffer, nal_unit_length, logctx) != 0) {
av_log(logctx, AV_LOG_ERROR, "Parsing of NAL unit failed\n");
return AVERROR_INVALIDDATA;
}
}
bytestream2_skip(&gb, nal_unit_length);
}
}
} else
return -1;
return ret;
}
static int evc_parse(AVCodecParserContext *s, AVCodecContext *avctx,
const uint8_t **poutbuf, int *poutbuf_size,
const uint8_t *buf, int buf_size)
{
int next;
int ret;
EVCParserContext *ctx = s->priv_data;
if (avctx->extradata && !ctx->parsed_extradata) {
decode_extradata(ctx, avctx->extradata, avctx->extradata_size, avctx);
ctx->parsed_extradata = 1;
}
next = buf_size;
ret = parse_nal_units(s, avctx, buf, buf_size);
if(ret < 0) {
*poutbuf = NULL;
*poutbuf_size = 0;
return buf_size;
}
s->picture_structure = AV_PICTURE_STRUCTURE_FRAME;
// poutbuf contains just one Access Unit
*poutbuf = buf;
*poutbuf_size = buf_size;
return next;
}
static void evc_parser_close(AVCodecParserContext *s)
{
EVCParserContext *ctx = s->priv_data;
ff_evc_parse_free(ctx);
}
const AVCodecParser ff_evc_parser = {
.codec_ids = { AV_CODEC_ID_EVC },
.priv_data_size = sizeof(EVCParserContext),
.parser_parse = evc_parse,
.parser_close = evc_parser_close,
};
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