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- // 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.
- #ifndef MEDIA_FILTERS_AUDIO_TIMESTAMP_VALIDATOR_H_
- #define MEDIA_FILTERS_AUDIO_TIMESTAMP_VALIDATOR_H_
- #include "base/memory/raw_ptr.h"
- #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 {
- public:
- AudioTimestampValidator(const AudioDecoderConfig& decoder_config,
- MediaLog* media_log);
- AudioTimestampValidator(const AudioTimestampValidator&) = delete;
- AudioTimestampValidator& operator=(const AudioTimestampValidator&) = delete;
- ~AudioTimestampValidator();
- // 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 DecoderBuffer& buffer);
- void RecordOutputDuration(const AudioBuffer& buffer);
- private:
- bool has_codec_delay_;
- raw_ptr<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_;
- // Tracks the number of MEDIA_LOG warnings when large timestamp gap detected.
- int num_timestamp_gap_warnings_ = 0;
- };
- } // namespace media
- #endif // MEDIA_FILTERS_AUDIO_TIMESTAMP_VALIDATOR_H_
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