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Fixing bitrate calculation (to be in bytes instead of bits), and adding in FPS detection for files which don't have valid FPS. In those cases (streaming files for example), we iterate through all packets, and average the # of frames, duration, bit rate, etc... Not idealy, but a better fallback.

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This commit is contained in:
Jonathan Thomas
2018-07-25 02:24:01 -05:00
parent 628eb37307
commit 93c1e2eb49
1 changed files with 41 additions and 71 deletions
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112
src/FFmpegReader.cpp
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@@ -339,19 +339,21 @@ void FFmpegReader::UpdateAudioInfo()
void FFmpegReader::UpdateVideoInfo()
{
if (check_fps)
// Already initialized all the video metadata, no reason to do it again
return;
// Set values of FileInfo struct
info.has_video = true;
info.file_size = pFormatCtx->pb ? avio_size(pFormatCtx->pb) : -1;
info.height = AV_GET_CODEC_ATTRIBUTES(pStream, pCodecCtx)->height;
info.width = AV_GET_CODEC_ATTRIBUTES(pStream, pCodecCtx)->width;
info.vcodec = pCodecCtx->codec->name;
info.video_bit_rate = pFormatCtx->bit_rate;
if (!check_fps)
{
// set frames per second (fps)
info.fps.num = pStream->avg_frame_rate.num;
info.fps.den = pStream->avg_frame_rate.den;
}
info.video_bit_rate = (pFormatCtx->bit_rate / 8);
// set frames per second (fps)
info.fps.num = pStream->avg_frame_rate.num;
info.fps.den = pStream->avg_frame_rate.den;
if (pStream->sample_aspect_ratio.num != 0)
{
@@ -415,16 +417,22 @@ void FFmpegReader::UpdateVideoInfo()
}
// Override an invalid framerate
if (info.fps.ToFloat() > 240.0f || (info.fps.num == 0 || info.fps.den == 0))
{
// Set a few important default video settings (so audio can be divided into frames)
info.fps.num = 24;
info.fps.den = 1;
info.video_timebase.num = 1;
info.video_timebase.den = 24;
if (info.fps.ToFloat() > 240.0f || (info.fps.num == 0 || info.fps.den == 0)) {
// Calculate FPS, duration, video bit rate, and video length manually
// by scanning through all the video stream packets
CheckFPS();
// Calculate number of frames
info.video_length = round(info.duration * info.fps.ToDouble());
// If still an invalid FPS detected, just default to 24 FPS
// Set a few important default video settings (so audio can be divided into frames)
if (info.fps.ToFloat() > 240.0f || (info.fps.num == 0 || info.fps.den == 0)) {
info.fps.num = 24;
info.fps.den = 1;
info.video_timebase.num = 1;
info.video_timebase.den = 24;
// Calculate number of frames
info.video_length = round(info.duration * info.fps.ToDouble());
}
}
// Add video metadata (if any)
@@ -1857,16 +1865,12 @@ void FFmpegReader::CheckWorkingFrames(bool end_of_stream, int64_t requested_fram
void FFmpegReader::CheckFPS()
{
check_fps = true;
AV_ALLOCATE_IMAGE(pFrame, AV_GET_CODEC_PIXEL_FORMAT(pStream, pCodecCtx), info.width, info.height);
int first_second_counter = 0;
int second_second_counter = 0;
int third_second_counter = 0;
int forth_second_counter = 0;
int fifth_second_counter = 0;
int iterations = 0;
int threshold = 500;
int frames_detected = 0;
// Loop through the stream
while (true)
@@ -1908,63 +1912,29 @@ void FFmpegReader::CheckFPS()
forth_second_counter++;
else if (video_seconds > 4.0 && video_seconds <= 5.0)
fifth_second_counter++;
else
// Too far
break;
// Increment counters
frames_detected++;
}
}
// Increment counters
iterations++;
// Give up (if threshold exceeded)
if (iterations > threshold)
break;
}
// Double check that all counters have greater than zero (or give up)
if (second_second_counter == 0 || third_second_counter == 0 || forth_second_counter == 0 || fifth_second_counter == 0)
{
// Seek to frame 1
Seek(1);
if (second_second_counter != 0 && third_second_counter != 0 && forth_second_counter != 0 && fifth_second_counter != 0) {
// Calculate average FPS
int sum_fps = second_second_counter + third_second_counter + forth_second_counter + fifth_second_counter;
int avg_fps = round(sum_fps / 4.0f);
// exit with no changes to FPS (not enough data to calculate)
return;
// Update FPS
info.fps = Fraction(avg_fps, 1);
// Update Duration and Length
info.video_length = frames_detected;
info.duration = frames_detected / round(sum_fps / 4.0f);
// Update video bit rate
info.video_bit_rate = info.file_size / info.duration;
}
int sum_fps = second_second_counter + third_second_counter + forth_second_counter + fifth_second_counter;
int avg_fps = round(sum_fps / 4.0f);
// Sometimes the FPS is incorrectly detected by FFmpeg. If the 1st and 2nd seconds counters
// agree with each other, we are going to adjust the FPS of this reader instance. Otherwise, print
// a warning message.
// Get diff from actual frame rate
double fps = info.fps.ToDouble();
double diff = fps - double(avg_fps);
// Is difference bigger than 1 frame?
if (diff <= -1 || diff >= 1)
{
// Compare to half the frame rate (the most common type of issue)
double half_fps = Fraction(info.fps.num / 2, info.fps.den).ToDouble();
diff = half_fps - double(avg_fps);
// Is difference bigger than 1 frame?
if (diff <= -1 || diff >= 1)
{
// Update FPS for this reader instance
info.fps = Fraction(avg_fps, 1);
}
else
{
// Update FPS for this reader instance (to 1/2 the original framerate)
info.fps = Fraction(info.fps.num / 2, info.fps.den);
}
}
// Seek to frame 1
Seek(1);
}
// Remove AVFrame from cache (and deallocate it's memory)