media/base/media_file_checker.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/base/media_file_checker.h"

#include <stddef.h>
#include <stdint.h>
#include <map>
#include <memory>
#include <utility>

#include "base/bind.h"
#include "base/time/time.h"
#include "media/ffmpeg/ffmpeg_common.h"
#include "media/ffmpeg/ffmpeg_deleters.h"
#include "media/filters/blocking_url_protocol.h"
#include "media/filters/ffmpeg_glue.h"
#include "media/filters/file_data_source.h"

namespace media {

static const int64_t kMaxCheckTimeInSeconds = 5;

static void OnError(bool* called) {
  *called = false;
}

MediaFileChecker::MediaFileChecker(base::File file) : file_(std::move(file)) {}

MediaFileChecker::~MediaFileChecker() {
}

bool MediaFileChecker::Start(base::TimeDelta check_time) {
  media::FileDataSource source(std::move(file_));
  bool read_ok = true;
  media::BlockingUrlProtocol protocol(&source, base::Bind(&OnError, &read_ok));
  media::FFmpegGlue glue(&protocol);
  AVFormatContext* format_context = glue.format_context();

  if (!glue.OpenContext())
    return false;

  if (avformat_find_stream_info(format_context, NULL) < 0)
    return false;

  // Remember the codec context for any decodable audio or video streams.
  std::map<int, std::unique_ptr<AVCodecContext, ScopedPtrAVFreeContext>>
      stream_contexts;
  for (size_t i = 0; i < format_context->nb_streams; ++i) {
    AVCodecParameters* cp = format_context->streams[i]->codecpar;

    if (cp->codec_type == AVMEDIA_TYPE_AUDIO ||
        cp->codec_type == AVMEDIA_TYPE_VIDEO) {
      std::unique_ptr<AVCodecContext, ScopedPtrAVFreeContext> c(
          AVStreamToAVCodecContext(format_context->streams[i]));
      if (!c)
        continue;
      AVCodec* codec = avcodec_find_decoder(cp->codec_id);
      if (codec && avcodec_open2(c.get(), codec, nullptr) >= 0)
        stream_contexts[i] = std::move(c);
    }
  }

  if (stream_contexts.size() == 0)
    return false;

  AVPacket packet;
  std::unique_ptr<AVFrame, media::ScopedPtrAVFreeFrame> frame(av_frame_alloc());
  int result = 0;

  const base::TimeTicks deadline = base::TimeTicks::Now() +
      std::min(check_time,
               base::TimeDelta::FromSeconds(kMaxCheckTimeInSeconds));
  do {
    result = av_read_frame(glue.format_context(), &packet);
    if (result < 0)
      break;

    std::map<int, std::unique_ptr<AVCodecContext, ScopedPtrAVFreeContext>>::
        const_iterator it = stream_contexts.find(packet.stream_index);
    if (it == stream_contexts.end()) {
      av_packet_unref(&packet);
      continue;
    }
    AVCodecContext* av_context = it->second.get();

    int frame_decoded = 0;
    if (av_context->codec_type == AVMEDIA_TYPE_AUDIO) {
      // A shallow copy of packet so we can slide packet.data as frames are
      // decoded; otherwise av_packet_unref() will corrupt memory.
      AVPacket temp_packet = packet;
      do {
        result = avcodec_decode_audio4(av_context, frame.get(), &frame_decoded,
                                       &temp_packet);
        if (result < 0)
          break;
        av_frame_unref(frame.get());
        temp_packet.size -= result;
        temp_packet.data += result;
        frame_decoded = 0;
      } while (temp_packet.size > 0);
    } else if (av_context->codec_type == AVMEDIA_TYPE_VIDEO) {
      result = avcodec_decode_video2(av_context, frame.get(), &frame_decoded,
                                     &packet);
      if (result >= 0 && frame_decoded)
        av_frame_unref(frame.get());
    }
    av_packet_unref(&packet);
  } while (base::TimeTicks::Now() < deadline && read_ok && result >= 0);

  stream_contexts.clear();
  return read_ok && (result == AVERROR_EOF || result >= 0);
}

}  // namespace media