blob: ba4c1bab5a9aa8c5d803a7b5828a5b7983b9e664 [file] [log] [blame]
// Copyright 2016 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 "base/memory/ref_counted.h"
#include "base/time/time.h"
#include "media/base/audio_buffer.h"
#include "media/base/audio_decoder_config.h"
#include "media/base/audio_timestamp_helper.h"
#include "media/base/decoder_buffer.h"
#include "media/base/media_log.h"
#include "media/base/timestamp_constants.h"
namespace media {
class MEDIA_EXPORT AudioTimestampValidator {
AudioTimestampValidator(const AudioDecoderConfig& decoder_config,
const scoped_refptr<MediaLog>& media_log);
// These methods monitor DecoderBuffer timestamps for gaps for the purpose of
// warning developers when gaps may cause AV sync drift. A DecoderBuffer's
// timestamp should roughly equal the timestamp of the previous buffer offset
// by the previous buffer's duration.
void CheckForTimestampGap(const scoped_refptr<DecoderBuffer>& buffer);
void RecordOutputDuration(const scoped_refptr<AudioBuffer>& buffer);
bool has_codec_delay_;
scoped_refptr<MediaLog> media_log_;
// Accumulates time from decoded audio frames. We adjust the base timestamp as
// needed for the first few buffers (stabilization period) of decoded output
// to account for pre-skip and codec delay. See CheckForTimestampGap().
std::unique_ptr<AudioTimestampHelper> audio_output_ts_helper_;
base::TimeDelta audio_base_ts_;
// Initially false, set to true when we observe gap between encoded timestamps
// match gap between output decoder buffers.
bool reached_stable_state_;
// Counts attempts to adjust |audio_output_ts_helper_| base offset in effort
// to form expectation for encoded timestamps based on decoded output. Give up
// making adjustments when count exceeds |limit_unstable_audio_tries_|.
int num_unstable_audio_tries_;
// Limits the number of attempts to stabilize audio timestamp expectations.
int limit_unstable_audio_tries_;
// How many milliseconds can DecoderBuffer timestamps differ from expectations
// before we MEDIA_LOG warn developers. Threshold initially set from
// kGapWarningThresholdMsec. Once hit, the threshold is increased by
// the detected gap amount. This avoids log spam while still emitting
// logs if things get worse. See CheckTimestampForGap().
uint32_t drift_warning_threshold_msec_;
} // namespace media