FFmpeg parser: better fallback for streams that do not expose bitrate

src/libs/audio/impl/ffmpeg/AudioFile.cpp

@@ -32,6 +32,7 @@ extern "C"
 }
 
 #include "core/ILogger.hpp"
+#include "core/ITraceLogger.hpp"
 #include "core/String.hpp"
 
 #include "audio/AudioTypes.hpp"
@@ -189,7 +190,7 @@ namespace lms::audio::ffmpeg
             std::array<char, 256> buffer{ 0 };
             std::vsnprintf(buffer.data(), buffer.size(), fmt, vl);
 
-            LMS_LOG(AUDIO, DEBUG, "ffmpeg [" << avLogLevelToStr(level) << "] " << buffer.data());
+            LMS_LOG(AUDIO, DEBUG, "FFmpeg [" << avLogLevelToStr(level) << "] " << buffer.data());
         }
 
         class AvInitializer
@@ -205,6 +206,8 @@ namespace lms::audio::ffmpeg
     AudioFile::AudioFile(const std::filesystem::path& p)
         : _p{ p }
     {
+        LMS_SCOPED_TRACE_DETAILED("MetaData", "FFmpegParseFile");
+
         static AvInitializer init;
 
         int error{ avformat_open_input(&_context, _p.c_str(), nullptr, nullptr) };
@@ -240,7 +243,8 @@ namespace lms::audio::ffmpeg
         info.container = avdemuxerToContainerType(_context->iformat->name);
         info.containerName = _context->iformat->name;
 
-        info.bitrate = _context->bit_rate;
+        if (_context->bit_rate > 0)
+            info.bitrate = _context->bit_rate;
         info.duration = std::chrono::milliseconds{ _context->duration == AV_NOPTS_VALUE ? 0 : _context->duration / AV_TIME_BASE * 1'000 };
 
         return info;

src/libs/audio/impl/ffmpeg/AudioFile.hpp

@@ -47,7 +47,7 @@ namespace lms::audio::ffmpeg
         std::optional<ContainerType> container;
         std::string containerName;
 
-        std::size_t bitrate{};
+        std::optional<std::size_t> bitrate;
         std::chrono::milliseconds duration{};
     };
 

src/libs/audio/impl/ffmpeg/AudioFileInfo.cpp

@@ -19,6 +19,9 @@
 
 #include "AudioFileInfo.hpp"
 
+#include <filesystem>
+#include <system_error>
+
 #include "core/ILogger.hpp"
 
 #include "audio/AudioTypes.hpp"
@@ -44,6 +47,12 @@ namespace lms::audio::ffmpeg
                 return audioProperties;
             }
 
+            if (containerInfo.duration.count() == 0)
+            {
+                LMS_LOG(AUDIO, DEBUG, "Cannot determine duration in " << audioFile.getPath());
+                return audioProperties;
+            }
+
             if (!containerInfo.container)
             {
                 LMS_LOG(AUDIO, DEBUG, "Unhandled container '" << containerInfo.containerName << "' in " << audioFile.getPath());
@@ -56,12 +65,6 @@ namespace lms::audio::ffmpeg
                 return audioProperties;
             }
 
-            if (!bestStreamInfo->bitrate || *bestStreamInfo->bitrate == 0)
-            {
-                LMS_LOG(AUDIO, DEBUG, "Cannot determine bitrate in " << audioFile.getPath());
-                return audioProperties;
-            }
-
             if (!bestStreamInfo->channelCount || *bestStreamInfo->channelCount == 0)
             {
                 LMS_LOG(AUDIO, DEBUG, "Cannot determine channel count in " << audioFile.getPath());
@@ -79,7 +82,27 @@ namespace lms::audio::ffmpeg
             audioProperties->container = *containerInfo.container;
             audioProperties->duration = containerInfo.duration;
             audioProperties->codec = *bestStreamInfo->codec;
-            audioProperties->bitrate = *bestStreamInfo->bitrate;
+
+            if (bestStreamInfo->bitrate)
+                audioProperties->bitrate = *bestStreamInfo->bitrate;
+            else if (containerInfo.bitrate)
+                audioProperties->bitrate = *containerInfo.bitrate;
+            else // Fallback on a bitrate based on duration/size
+            {
+                std::error_code ec;
+                const auto fileSize{ std::filesystem::file_size(audioFile.getPath(), ec) };
+                if (ec)
+                {
+                    LMS_LOG(AUDIO, DEBUG, "Cannot determine file size for " << audioFile.getPath() << ": " << ec.message());
+                    audioProperties.reset();
+                    return audioProperties;
+                }
+
+                audioProperties->bitrate = static_cast<std::size_t>(std::chrono::duration_cast<std::chrono::duration<double>>(containerInfo.duration).count() / fileSize);
+                LMS_LOG(AUDIO, DEBUG, "Estimated bitrate from duration/size: " << audioProperties->bitrate << " bps in " << audioFile.getPath());
+            }
+            assert(audioProperties->bitrate > 0);
+
             audioProperties->channelCount = *bestStreamInfo->channelCount;
             audioProperties->sampleRate = *bestStreamInfo->sampleRate;
             audioProperties->bitsPerSample = bestStreamInfo->bitsPerSample;