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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "media/base/video_decoder.h"
#include "base/command_line.h"
#include "base/strings/string_number_conversions.h"
#include "base/system/sys_info.h"
#include "media/base/limits.h"
#include "media/base/media_switches.h"
#include "media/base/video_frame.h"
namespace media {
VideoDecoder::VideoDecoder() = default;
VideoDecoder::~VideoDecoder() = default;
bool VideoDecoder::IsPlatformDecoder() const {
return false;
}
bool VideoDecoder::NeedsBitstreamConversion() const {
return false;
}
bool VideoDecoder::CanReadWithoutStalling() const {
return true;
}
int VideoDecoder::GetMaxDecodeRequests() const {
return 1;
}
// static
int VideoDecoder::GetRecommendedThreadCount(int desired_threads) {
// If the thread count is specified on the command line, respect it so long as
// it's greater than zero.
const auto threads =
base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
switches::kVideoThreads);
int decode_threads;
if (base::StringToInt(threads, &decode_threads) && decode_threads > 0)
return decode_threads;
// Clamp to the number of available logical processors/cores.
desired_threads =
std::min(desired_threads, base::SysInfo::NumberOfProcessors());
// Always try to use at least two threads for video decoding. There is little
// reason not to since current day CPUs tend to be multi-core and we measured
// performance benefits on older machines such as P4s with hyperthreading.
//
// All our software video decoders treat having one thread the same as having
// zero threads; I.e., decoding will execute on the calling thread. Therefore,
// at least two threads are required to allow decoding to progress outside of
// each Decode() call.
return std::min(std::max(desired_threads,
static_cast<int>(limits::kMinVideoDecodeThreads)),
static_cast<int>(limits::kMaxVideoDecodeThreads));
}
} // namespace media
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