media/capture/video/file_video_capture_device.cc

// Copyright 2013 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/capture/video/file_video_capture_device.h"

#include <stddef.h>
#include <utility>

#include "base/bind.h"
#include "base/macros.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_piece.h"
#include "media/base/video_capture_types.h"
#include "media/filters/jpeg_parser.h"

namespace media {

static const int kY4MHeaderMaxSize = 200;
static const char kY4MSimpleFrameDelimiter[] = "FRAME";
static const int kY4MSimpleFrameDelimiterSize = 6;
static const float kMJpegFrameRate = 30.0f;

int ParseY4MInt(const base::StringPiece& token) {
  int temp_int;
  CHECK(base::StringToInt(token, &temp_int)) << token;
  return temp_int;
}

// Extract numerator and denominator out of a token that must have the aspect
// numerator:denominator, both integer numbers.
void ParseY4MRational(const base::StringPiece& token,
                      int* numerator, int* denominator) {
  size_t index_divider = token.find(':');
  CHECK_NE(index_divider, token.npos);
  *numerator = ParseY4MInt(token.substr(0, index_divider));
  *denominator = ParseY4MInt(token.substr(index_divider + 1, token.length()));
  CHECK(*denominator);
}

// This function parses the ASCII string in |header| as belonging to a Y4M file,
// returning the collected format in |video_format|. For a non authoritative
// explanation of the header format, check
// http://wiki.multimedia.cx/index.php?title=YUV4MPEG2
// Restrictions: Only interlaced I420 pixel format is supported, and pixel
// aspect ratio is ignored.
// Implementation notes: Y4M header should end with an ASCII 0x20 (whitespace)
// character, however all examples mentioned in the Y4M header description end
// with a newline character instead. Also, some headers do _not_ specify pixel
// format, in this case it means I420.
// This code was inspired by third_party/libvpx_new/.../y4minput.* .
void ParseY4MTags(const std::string& file_header,
                  media::VideoCaptureFormat* video_format) {
  media::VideoCaptureFormat format;
  format.pixel_format = media::PIXEL_FORMAT_I420;
  size_t index = 0;
  size_t blank_position = 0;
  base::StringPiece token;
  while ((blank_position = file_header.find_first_of("\n ", index)) !=
         std::string::npos) {
    // Every token is supposed to have an identifier letter and a bunch of
    // information immediately after, which we extract into a |token| here.
    token =
        base::StringPiece(&file_header[index + 1], blank_position - index - 1);
    CHECK(!token.empty());
    switch (file_header[index]) {
      case 'W':
        format.frame_size.set_width(ParseY4MInt(token));
        break;
      case 'H':
        format.frame_size.set_height(ParseY4MInt(token));
        break;
      case 'F': {
        // If the token is "FRAME", it means we have finished with the header.
        if (token[0] == 'R')
          break;
        int fps_numerator, fps_denominator;
        ParseY4MRational(token, &fps_numerator, &fps_denominator);
        format.frame_rate = fps_numerator / fps_denominator;
        break;
      }
      case 'I':
        // Interlacing is ignored, but we don't like mixed modes.
        CHECK_NE(token[0], 'm');
        break;
      case 'A':
        // Pixel aspect ratio ignored.
        break;
      case 'C':
        CHECK(token == "420" || token == "420jpeg" || token == "420paldv")
            << token;  // Only I420 is supported, and we fudge the variants.
        break;
      default:
        break;
    }
    // We're done if we have found a newline character right after the token.
    if (file_header[blank_position] == '\n')
      break;
    index = blank_position + 1;
  }
  // Last video format semantic correctness check before sending it back.
  CHECK(format.IsValid());
  *video_format = format;
}

class VideoFileParser {
 public:
  explicit VideoFileParser(const base::FilePath& file_path);
  virtual ~VideoFileParser();

  // Parses file header and collects format information in |capture_format|.
  virtual bool Initialize(media::VideoCaptureFormat* capture_format) = 0;

  // Gets the start pointer of next frame and stores current frame size in
  // |frame_size|.
  virtual const uint8_t* GetNextFrame(int* frame_size) = 0;

 protected:
  const base::FilePath file_path_;
  int frame_size_;
  size_t current_byte_index_;
  size_t first_frame_byte_index_;
};

class Y4mFileParser final : public VideoFileParser {
 public:
  explicit Y4mFileParser(const base::FilePath& file_path);

  // VideoFileParser implementation, class methods.
  ~Y4mFileParser() override;
  bool Initialize(media::VideoCaptureFormat* capture_format) override;
  const uint8_t* GetNextFrame(int* frame_size) override;

 private:
  scoped_ptr<base::File> file_;
  scoped_ptr<uint8_t[]> video_frame_;

  DISALLOW_COPY_AND_ASSIGN(Y4mFileParser);
};

class MjpegFileParser final : public VideoFileParser {
 public:
  explicit MjpegFileParser(const base::FilePath& file_path);

  // VideoFileParser implementation, class methods.
  ~MjpegFileParser() override;
  bool Initialize(media::VideoCaptureFormat* capture_format) override;
  const uint8_t* GetNextFrame(int* frame_size) override;

 private:
  scoped_ptr<base::MemoryMappedFile> mapped_file_;

  DISALLOW_COPY_AND_ASSIGN(MjpegFileParser);
};

VideoFileParser::VideoFileParser(const base::FilePath& file_path)
    : file_path_(file_path),
      frame_size_(0),
      current_byte_index_(0),
      first_frame_byte_index_(0) {}

VideoFileParser::~VideoFileParser() {}

Y4mFileParser::Y4mFileParser(const base::FilePath& file_path)
    : VideoFileParser(file_path) {}

Y4mFileParser::~Y4mFileParser() {}

bool Y4mFileParser::Initialize(media::VideoCaptureFormat* capture_format) {
  file_.reset(new base::File(file_path_,
                             base::File::FLAG_OPEN | base::File::FLAG_READ));
  if (!file_->IsValid()) {
    DLOG(ERROR) << file_path_.value() << ", error: "
                << base::File::ErrorToString(file_->error_details());
    return false;
  }

  std::string header(kY4MHeaderMaxSize, '\0');
  file_->Read(0, &header[0], header.size());
  const size_t header_end = header.find(kY4MSimpleFrameDelimiter);
  CHECK_NE(header_end, header.npos);

  ParseY4MTags(header, capture_format);
  first_frame_byte_index_ = header_end + kY4MSimpleFrameDelimiterSize;
  current_byte_index_ = first_frame_byte_index_;
  frame_size_ = capture_format->ImageAllocationSize();
  return true;
}

const uint8_t* Y4mFileParser::GetNextFrame(int* frame_size) {
  if (!video_frame_)
    video_frame_.reset(new uint8_t[frame_size_]);
  int result =
      file_->Read(current_byte_index_,
                  reinterpret_cast<char*>(video_frame_.get()), frame_size_);

  // If we passed EOF to base::File, it will return 0 read characters. In that
  // case, reset the pointer and read again.
  if (result != frame_size_) {
    CHECK_EQ(result, 0);
    current_byte_index_ = first_frame_byte_index_;
    CHECK_EQ(
        file_->Read(current_byte_index_,
                    reinterpret_cast<char*>(video_frame_.get()), frame_size_),
        frame_size_);
  } else {
    current_byte_index_ += frame_size_ + kY4MSimpleFrameDelimiterSize;
  }
  *frame_size = frame_size_;
  return video_frame_.get();
}

MjpegFileParser::MjpegFileParser(const base::FilePath& file_path)
    : VideoFileParser(file_path) {}

MjpegFileParser::~MjpegFileParser() {}

bool MjpegFileParser::Initialize(media::VideoCaptureFormat* capture_format) {
  mapped_file_.reset(new base::MemoryMappedFile());

  if (!mapped_file_->Initialize(file_path_) || !mapped_file_->IsValid()) {
    LOG(ERROR) << "File memory map error: " << file_path_.value();
    return false;
  }

  JpegParseResult result;
  if (!ParseJpegStream(mapped_file_->data(), mapped_file_->length(), &result))
    return false;

  frame_size_ = result.image_size;
  if (frame_size_ > static_cast<int>(mapped_file_->length())) {
    LOG(ERROR) << "File is incomplete";
    return false;
  }

  VideoCaptureFormat format;
  format.pixel_format = media::PIXEL_FORMAT_MJPEG;
  format.frame_size.set_width(result.frame_header.visible_width);
  format.frame_size.set_height(result.frame_header.visible_height);
  format.frame_rate = kMJpegFrameRate;
  if (!format.IsValid())
    return false;
  *capture_format = format;
  return true;
}

const uint8_t* MjpegFileParser::GetNextFrame(int* frame_size) {
  const uint8_t* buf_ptr = mapped_file_->data() + current_byte_index_;

  JpegParseResult result;
  if (!ParseJpegStream(buf_ptr, mapped_file_->length() - current_byte_index_,
                       &result)) {
    return nullptr;
  }
  *frame_size = frame_size_ = result.image_size;
  current_byte_index_ += frame_size_;
  // Reset the pointer to play repeatedly.
  if (current_byte_index_ >= mapped_file_->length())
    current_byte_index_ = first_frame_byte_index_;
  return buf_ptr;
}

// static
bool FileVideoCaptureDevice::GetVideoCaptureFormat(
    const base::FilePath& file_path,
    media::VideoCaptureFormat* video_format) {
  scoped_ptr<VideoFileParser> file_parser =
      GetVideoFileParser(file_path, video_format);
  return file_parser != nullptr;
}

// static
scoped_ptr<VideoFileParser>
FileVideoCaptureDevice::GetVideoFileParser(
    const base::FilePath& file_path,
    media::VideoCaptureFormat* video_format) {
  scoped_ptr<VideoFileParser> file_parser;
  std::string file_name(file_path.value().begin(), file_path.value().end());

  if (base::EndsWith(file_name, "y4m",
                     base::CompareCase::INSENSITIVE_ASCII)) {
    file_parser.reset(new Y4mFileParser(file_path));
  } else if (base::EndsWith(file_name, "mjpeg",
                            base::CompareCase::INSENSITIVE_ASCII)) {
    file_parser.reset(new MjpegFileParser(file_path));
  } else {
    LOG(ERROR) << "Unsupported file format.";
    return file_parser;
  }

  if (!file_parser->Initialize(video_format)) {
    file_parser.reset();
  }
  return file_parser;
}

FileVideoCaptureDevice::FileVideoCaptureDevice(const base::FilePath& file_path)
    : capture_thread_("CaptureThread"), file_path_(file_path) {}

FileVideoCaptureDevice::~FileVideoCaptureDevice() {
  DCHECK(thread_checker_.CalledOnValidThread());
  // Check if the thread is running.
  // This means that the device have not been DeAllocated properly.
  CHECK(!capture_thread_.IsRunning());
}

void FileVideoCaptureDevice::AllocateAndStart(
    const VideoCaptureParams& params,
    scoped_ptr<VideoCaptureDevice::Client> client) {
  DCHECK(thread_checker_.CalledOnValidThread());
  CHECK(!capture_thread_.IsRunning());

  capture_thread_.Start();
  capture_thread_.message_loop()->PostTask(
      FROM_HERE,
      base::Bind(&FileVideoCaptureDevice::OnAllocateAndStart,
                 base::Unretained(this), params, base::Passed(&client)));
}

void FileVideoCaptureDevice::StopAndDeAllocate() {
  DCHECK(thread_checker_.CalledOnValidThread());
  CHECK(capture_thread_.IsRunning());

  capture_thread_.message_loop()->PostTask(
      FROM_HERE, base::Bind(&FileVideoCaptureDevice::OnStopAndDeAllocate,
                            base::Unretained(this)));
  capture_thread_.Stop();
}

void FileVideoCaptureDevice::OnAllocateAndStart(
    const VideoCaptureParams& params,
    scoped_ptr<VideoCaptureDevice::Client> client) {
  DCHECK_EQ(capture_thread_.message_loop(), base::MessageLoop::current());

  client_ = std::move(client);

  DCHECK(!file_parser_);
  file_parser_ = GetVideoFileParser(file_path_, &capture_format_);
  if (!file_parser_) {
    client_->OnError(FROM_HERE, "Could not open Video file");
    return;
  }

  DVLOG(1) << "Opened video file " << capture_format_.frame_size.ToString()
           << ", fps: " << capture_format_.frame_rate;

  capture_thread_.message_loop()->PostTask(
      FROM_HERE, base::Bind(&FileVideoCaptureDevice::OnCaptureTask,
                            base::Unretained(this)));
}

void FileVideoCaptureDevice::OnStopAndDeAllocate() {
  DCHECK_EQ(capture_thread_.message_loop(), base::MessageLoop::current());
  file_parser_.reset();
  client_.reset();
  next_frame_time_ = base::TimeTicks();
}

void FileVideoCaptureDevice::OnCaptureTask() {
  DCHECK_EQ(capture_thread_.message_loop(), base::MessageLoop::current());
  if (!client_)
    return;

  // Give the captured frame to the client.
  int frame_size = 0;
  const uint8_t* frame_ptr = file_parser_->GetNextFrame(&frame_size);
  DCHECK(frame_size);
  CHECK(frame_ptr);
  const base::TimeTicks current_time = base::TimeTicks::Now();
  client_->OnIncomingCapturedData(frame_ptr, frame_size, capture_format_, 0,
                                  current_time);
  // Reschedule next CaptureTask.
  const base::TimeDelta frame_interval =
      base::TimeDelta::FromMicroseconds(1E6 / capture_format_.frame_rate);
  if (next_frame_time_.is_null()) {
    next_frame_time_ = current_time + frame_interval;
  } else {
    next_frame_time_ += frame_interval;
    // Don't accumulate any debt if we are lagging behind - just post next frame
    // immediately and continue as normal.
    if (next_frame_time_ < current_time)
      next_frame_time_ = current_time;
  }
  base::MessageLoop::current()->PostDelayedTask(
      FROM_HERE, base::Bind(&FileVideoCaptureDevice::OnCaptureTask,
                            base::Unretained(this)),
      next_frame_time_ - current_time);
}

}  // namespace media