ref: 122a74eda7011f3f6b95b075054a25d171abaca5
dir: /webmdec.cc/
/*
* Copyright (c) 2013 The WebM project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "./webmdec.h"
#include <cstring>
#include <cstdio>
#include "third_party/libwebm/mkvparser/mkvparser.h"
#include "third_party/libwebm/mkvparser/mkvreader.h"
namespace {
void reset(struct WebmInputContext *const webm_ctx) {
if (webm_ctx->reader != nullptr) {
mkvparser::MkvReader *const reader =
reinterpret_cast<mkvparser::MkvReader *>(webm_ctx->reader);
delete reader;
}
if (webm_ctx->segment != nullptr) {
mkvparser::Segment *const segment =
reinterpret_cast<mkvparser::Segment *>(webm_ctx->segment);
delete segment;
}
if (webm_ctx->buffer != nullptr) {
delete[] webm_ctx->buffer;
}
webm_ctx->reader = nullptr;
webm_ctx->segment = nullptr;
webm_ctx->buffer = nullptr;
webm_ctx->cluster = nullptr;
webm_ctx->block_entry = nullptr;
webm_ctx->block = nullptr;
webm_ctx->block_frame_index = 0;
webm_ctx->video_track_index = 0;
webm_ctx->timestamp_ns = 0;
webm_ctx->is_key_frame = false;
}
void get_first_cluster(struct WebmInputContext *const webm_ctx) {
mkvparser::Segment *const segment =
reinterpret_cast<mkvparser::Segment *>(webm_ctx->segment);
const mkvparser::Cluster *const cluster = segment->GetFirst();
webm_ctx->cluster = cluster;
}
void rewind_and_reset(struct WebmInputContext *const webm_ctx,
struct VpxInputContext *const vpx_ctx) {
rewind(vpx_ctx->file);
reset(webm_ctx);
}
} // namespace
int file_is_webm(struct WebmInputContext *webm_ctx,
struct VpxInputContext *vpx_ctx) {
mkvparser::MkvReader *const reader = new mkvparser::MkvReader(vpx_ctx->file);
webm_ctx->reader = reader;
webm_ctx->reached_eos = 0;
mkvparser::EBMLHeader header;
long long pos = 0;
if (header.Parse(reader, pos) < 0) {
rewind_and_reset(webm_ctx, vpx_ctx);
return 0;
}
mkvparser::Segment *segment;
if (mkvparser::Segment::CreateInstance(reader, pos, segment)) {
rewind_and_reset(webm_ctx, vpx_ctx);
return 0;
}
webm_ctx->segment = segment;
if (segment->Load() < 0) {
rewind_and_reset(webm_ctx, vpx_ctx);
return 0;
}
const mkvparser::Tracks *const tracks = segment->GetTracks();
const mkvparser::VideoTrack *video_track = nullptr;
for (unsigned long i = 0; i < tracks->GetTracksCount(); ++i) {
const mkvparser::Track *const track = tracks->GetTrackByIndex(i);
if (track->GetType() == mkvparser::Track::kVideo) {
video_track = static_cast<const mkvparser::VideoTrack *>(track);
webm_ctx->video_track_index = static_cast<int>(track->GetNumber());
break;
}
}
if (video_track == nullptr || video_track->GetCodecId() == nullptr) {
rewind_and_reset(webm_ctx, vpx_ctx);
return 0;
}
if (!strncmp(video_track->GetCodecId(), "V_VP8", 5)) {
vpx_ctx->fourcc = VP8_FOURCC;
} else if (!strncmp(video_track->GetCodecId(), "V_VP9", 5)) {
vpx_ctx->fourcc = VP9_FOURCC;
} else {
rewind_and_reset(webm_ctx, vpx_ctx);
return 0;
}
vpx_ctx->framerate.denominator = 0;
vpx_ctx->framerate.numerator = 0;
vpx_ctx->width = static_cast<uint32_t>(video_track->GetWidth());
vpx_ctx->height = static_cast<uint32_t>(video_track->GetHeight());
get_first_cluster(webm_ctx);
return 1;
}
int webm_read_frame(struct WebmInputContext *webm_ctx, uint8_t **buffer,
size_t *buffer_size) {
// This check is needed for frame parallel decoding, in which case this
// function could be called even after it has reached end of input stream.
if (webm_ctx->reached_eos) {
return 1;
}
mkvparser::Segment *const segment =
reinterpret_cast<mkvparser::Segment *>(webm_ctx->segment);
const mkvparser::Cluster *cluster =
reinterpret_cast<const mkvparser::Cluster *>(webm_ctx->cluster);
const mkvparser::Block *block =
reinterpret_cast<const mkvparser::Block *>(webm_ctx->block);
const mkvparser::BlockEntry *block_entry =
reinterpret_cast<const mkvparser::BlockEntry *>(webm_ctx->block_entry);
bool block_entry_eos = false;
do {
long status = 0;
bool get_new_block = false;
if (block_entry == nullptr && !block_entry_eos) {
status = cluster->GetFirst(block_entry);
get_new_block = true;
} else if (block_entry_eos || block_entry->EOS()) {
cluster = segment->GetNext(cluster);
if (cluster == nullptr || cluster->EOS()) {
*buffer_size = 0;
webm_ctx->reached_eos = 1;
return 1;
}
status = cluster->GetFirst(block_entry);
block_entry_eos = false;
get_new_block = true;
} else if (block == nullptr ||
webm_ctx->block_frame_index == block->GetFrameCount() ||
block->GetTrackNumber() != webm_ctx->video_track_index) {
status = cluster->GetNext(block_entry, block_entry);
if (block_entry == nullptr || block_entry->EOS()) {
block_entry_eos = true;
continue;
}
get_new_block = true;
}
if (status || block_entry == nullptr) {
return -1;
}
if (get_new_block) {
block = block_entry->GetBlock();
if (block == nullptr) return -1;
webm_ctx->block_frame_index = 0;
}
} while (block_entry_eos ||
block->GetTrackNumber() != webm_ctx->video_track_index);
webm_ctx->cluster = cluster;
webm_ctx->block_entry = block_entry;
webm_ctx->block = block;
const mkvparser::Block::Frame &frame =
block->GetFrame(webm_ctx->block_frame_index);
++webm_ctx->block_frame_index;
if (frame.len > static_cast<long>(*buffer_size)) {
delete[] * buffer;
*buffer = new uint8_t[frame.len];
if (*buffer == nullptr) {
return -1;
}
webm_ctx->buffer = *buffer;
}
*buffer_size = frame.len;
webm_ctx->timestamp_ns = block->GetTime(cluster);
webm_ctx->is_key_frame = block->IsKey();
mkvparser::MkvReader *const reader =
reinterpret_cast<mkvparser::MkvReader *>(webm_ctx->reader);
return frame.Read(reader, *buffer) ? -1 : 0;
}
int webm_guess_framerate(struct WebmInputContext *webm_ctx,
struct VpxInputContext *vpx_ctx) {
uint32_t i = 0;
uint8_t *buffer = nullptr;
size_t buffer_size = 0;
while (webm_ctx->timestamp_ns < 1000000000 && i < 50) {
if (webm_read_frame(webm_ctx, &buffer, &buffer_size)) {
break;
}
++i;
}
vpx_ctx->framerate.numerator = (i - 1) * 1000000;
vpx_ctx->framerate.denominator =
static_cast<int>(webm_ctx->timestamp_ns / 1000);
delete[] buffer;
get_first_cluster(webm_ctx);
webm_ctx->block = nullptr;
webm_ctx->block_entry = nullptr;
webm_ctx->block_frame_index = 0;
webm_ctx->timestamp_ns = 0;
webm_ctx->reached_eos = 0;
return 0;
}
void webm_free(struct WebmInputContext *webm_ctx) { reset(webm_ctx); }