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Make the video decoders' FFmpeg calls safe from several threads #6557

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Merged
jantonguirao merged 3 commits into from
Oct 27, 2026
Merged

Make the video decoders' FFmpeg calls safe from several threads #6557

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0396778
Make the video decoders' FFmpeg helpers safe from several threads
jantonguirao Oct 27, 2026
0d7be21
Set FFmpeg's log level from every video decoder again, as before
jantonguirao Oct 27, 2026
5b4cb1f
Set FFmpeg's log level once, when the library is loaded
jantonguirao Oct 27, 2026
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16 changes: 13 additions & 3 deletions dali/operators/video/frames_decoder_base.cc
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
// Copyright (c) 2021-2024, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
// Copyright (c) 2021-2026, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
Expand All @@ -21,6 +21,18 @@

namespace dali {

namespace {

// FFmpeg's log level is a plain global (av_log_set_level only stores it). It is set once, while the
// library is loaded and before any decoder exists, rather than by every decoder: decoders are
// created on several threads
const bool av_log_level_set = [] {
av_log_set_level(AV_LOG_ERROR);
return true;
}();

} // namespace

int MemoryVideoFile::Read(unsigned char *buffer, int buffer_size) {
int left_in_file = size_ - position_;
if (left_in_file <= 0) {
Expand Down Expand Up @@ -213,7 +225,6 @@ bool FramesDecoderBase::CheckDimensions() {
}

FramesDecoderBase::FramesDecoderBase(const std::string &filename, DALIImageType image_type) {
av_log_set_level(AV_LOG_ERROR);
filename_ = filename;
DALI_ENFORCE(image_type == DALI_YCbCr || image_type == DALI_RGB,
make_string("Invalid image type: ", image_type));
Expand All @@ -234,7 +245,6 @@ FramesDecoderBase::FramesDecoderBase(const std::string &filename, DALIImageType
}

FramesDecoderBase::FramesDecoderBase(const char *memory_file, size_t memory_file_size, std::string_view source_info, DALIImageType image_type) {
av_log_set_level(AV_LOG_ERROR);
filename_ = source_info;
DALI_ENFORCE(image_type == DALI_YCbCr || image_type == DALI_RGB,
make_string("Invalid image type: ", image_type));
Expand Down
6 changes: 3 additions & 3 deletions dali/operators/video/video_utils.cc
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
// Copyright (c) 2025, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
// Copyright (c) 2025-2026, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
Expand All @@ -19,6 +19,7 @@
#include <fstream>
#include <sstream>
#include <string>
#include <utility>

namespace dali {

Expand Down Expand Up @@ -148,8 +149,7 @@ std::vector<VideoFileMeta> GetVideoFiles(const std::string& file_root,
}

std::string av_error_string(int ret) {
static char msg[AV_ERROR_MAX_STRING_SIZE];
memset(msg, 0, sizeof(msg));
char msg[AV_ERROR_MAX_STRING_SIZE] = {}; // not static: decoders run on several threads
return std::string(av_make_error_string(msg, AV_ERROR_MAX_STRING_SIZE, ret));
}

Expand Down
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