From 2ba67bc24cf6116349ad16d3bfa1a121c95a3173 Mon Sep 17 00:00:00 2001 From: SteveR-PMP <122415851+SteveR-PMP@users.noreply.github.com> Date: Thu, 8 Feb 2024 10:39:50 -0800 Subject: [PATCH] feat: default text zero bias (#1330) A positive value, in milliseconds. It is the threshold used to determine if we should assume that the text stream actually starts at time zero. If the first sample comes before default_text_zero_bias_ms, then the start will be padded as the stream is assumed to start at zero. If the first sample comes after default_text_zero_bias_ms then the start of the stream will not be padded as we cannot assume the start time of the stream. --- include/packager/packager.h | 4 ++++ packager/app/muxer_flags.cc | 11 +++++++++++ packager/app/muxer_flags.h | 1 + packager/app/packager_main.cc | 2 ++ packager/media/formats/webvtt/text_padder.cc | 4 +++- packager/packager.cc | 6 ++---- 6 files changed, 23 insertions(+), 5 deletions(-) diff --git a/include/packager/packager.h b/include/packager/packager.h index 6c7ad7a260..96fd0b0720 100644 --- a/include/packager/packager.h +++ b/include/packager/packager.h @@ -46,6 +46,10 @@ struct PackagingParams { /// audio) timestamps to compensate for possible negative timestamps in the /// input. int32_t transport_stream_timestamp_offset_ms = 0; + // the threshold used to determine if we should assume that the text stream + // actually starts at time zero + int32_t default_text_zero_bias_ms = 0; + /// Chunking (segmentation) related parameters. ChunkingParams chunking_params; diff --git a/packager/app/muxer_flags.cc b/packager/app/muxer_flags.cc index bbee0ccf04..2a68b1ee91 100644 --- a/packager/app/muxer_flags.cc +++ b/packager/app/muxer_flags.cc @@ -62,3 +62,14 @@ ABSL_FLAG(int32_t, "input. For example, timestamps from ISO-BMFF after adjusted by " "EditList could be negative. In transport streams, timestamps are " "not allowed to be less than zero."); +ABSL_FLAG( + int32_t, + default_text_zero_bias_ms, + 0, + "A positive value, in milliseconds. It is the threshold used to " + "determine if we should assume that the text stream actually starts " + "at time zero. If the first sample comes before default_text_zero_bias_ms, " + "then the start will be padded as the stream is assumed to start at zero. " + "If the first sample comes after default_text_zero_bias_ms then the start " + "of the stream will not be padded as we cannot assume the start time of " + "the stream."); diff --git a/packager/app/muxer_flags.h b/packager/app/muxer_flags.h index 20ee2f72b7..a27aff8638 100644 --- a/packager/app/muxer_flags.h +++ b/packager/app/muxer_flags.h @@ -21,5 +21,6 @@ ABSL_DECLARE_FLAG(bool, generate_sidx_in_media_segments); ABSL_DECLARE_FLAG(std::string, temp_dir); ABSL_DECLARE_FLAG(bool, mp4_include_pssh_in_stream); ABSL_DECLARE_FLAG(int32_t, transport_stream_timestamp_offset_ms); +ABSL_DECLARE_FLAG(int32_t, default_text_zero_bias_ms); #endif // APP_MUXER_FLAGS_H_ diff --git a/packager/app/packager_main.cc b/packager/app/packager_main.cc index 7651a0cd01..9e12798d60 100644 --- a/packager/app/packager_main.cc +++ b/packager/app/packager_main.cc @@ -461,6 +461,8 @@ std::optional GetPackagingParams() { packaging_params.transport_stream_timestamp_offset_ms = absl::GetFlag(FLAGS_transport_stream_timestamp_offset_ms); + packaging_params.default_text_zero_bias_ms = + absl::GetFlag(FLAGS_default_text_zero_bias_ms); packaging_params.output_media_info = absl::GetFlag(FLAGS_output_media_info); diff --git a/packager/media/formats/webvtt/text_padder.cc b/packager/media/formats/webvtt/text_padder.cc index 8bb9cf4c6c..f93b60200b 100644 --- a/packager/media/formats/webvtt/text_padder.cc +++ b/packager/media/formats/webvtt/text_padder.cc @@ -40,7 +40,9 @@ Status TextPadder::OnTextSample(std::unique_ptr data) { // start at time zero. if (max_end_time_ms_ < 0) { max_end_time_ms_ = - sample.start_time() > zero_start_bias_ms_ ? sample.start_time() : 0; + zero_start_bias_ms_ && sample.start_time() > zero_start_bias_ms_ + ? sample.start_time() + : 0; } // Check if there will be a gap between samples if we just dispatch this diff --git a/packager/packager.cc b/packager/packager.cc index 8f0196322d..05993f978d 100644 --- a/packager/packager.cc +++ b/packager/packager.cc @@ -59,8 +59,6 @@ namespace { const char kMediaInfoSuffix[] = ".media_info"; -const int64_t kDefaultTextZeroBiasMs = 10 * 60 * 1000; // 10 minutes - MuxerListenerFactory::StreamData ToMuxerListenerData( const StreamDescriptor& stream) { MuxerListenerFactory::StreamData data; @@ -662,8 +660,8 @@ Status CreateAudioVideoJobs( std::vector> handlers; if (is_text) { - handlers.emplace_back( - std::make_shared(kDefaultTextZeroBiasMs)); + handlers.emplace_back(std::make_shared( + packaging_params.default_text_zero_bias_ms)); } if (sync_points) { handlers.emplace_back(cue_aligner);