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Added a method to get the average # of frames over the initial 5 seconds of video, and adjust an invalid framerate, which sometimes FFmpeg detects. Also, a Reader only initializes it's default values 1 time, and only checks frame rate 1 time, regardless of how many times your Open() and Close() the reader.

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This commit is contained in:
Jonathan Thomas
2011-12-15 16:11:48 -06:00
parent ade29c7d68
commit f00c4206be
3 changed files with 107 additions and 6 deletions
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104
src/FFmpegReader.cpp
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@@ -5,11 +5,15 @@ using namespace openshot;
FFmpegReader::FFmpegReader(string path) throw(InvalidFile, NoStreamsFound, InvalidCodec)
: last_video_frame(0), last_audio_frame(0), is_seeking(0), seeking_pts(0), seeking_frame(0),
audio_pts_offset(99999), video_pts_offset(99999), working_cache(50), path(path),
is_video_seek(true), check_interlace(false), enable_seek(true) {
is_video_seek(true), check_interlace(false), check_fps(false), init_settings(false), enable_seek(true) {
// Open the file (if possible)
Open();
// Check for the correct frames per second (only once)
if (info.has_video)
CheckFPS();
// Get Frame 1 (to determine the offset between the PTS and the Frame Number)
GetFrame(1);
}
@@ -48,7 +52,11 @@ void FFmpegReader::Open()
throw NoStreamsFound("No video or audio streams found in this file.", path);
// Init FileInfo struct (clear all values)
InitFileInfo();
if (!init_settings)
{
InitFileInfo();
init_settings = true;
}
// Is there a video stream?
if (videoStream != -1)
@@ -160,8 +168,11 @@ void FFmpegReader::UpdateVideoInfo()
info.width = pCodecCtx->width;
info.vcodec = pCodecCtx->codec->name;
info.video_bit_rate = pFormatCtx->bit_rate;
info.fps.num = pStream->r_frame_rate.num;
info.fps.den = pStream->r_frame_rate.den;
if (!check_fps)
{
info.fps.num = pStream->r_frame_rate.num;
info.fps.den = pStream->r_frame_rate.den;
}
if (pStream->sample_aspect_ratio.num != 0)
{
info.pixel_ratio.num = pStream->sample_aspect_ratio.num;
@@ -893,3 +904,88 @@ void FFmpegReader::CheckWorkingFrames(bool end_of_stream)
}
}
// Check for the correct frames per second (FPS) value by scanning the 1st few seconds of video packets.
void FFmpegReader::CheckFPS()
{
check_fps = true;
pFrame = avcodec_alloc_frame();
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;
// Loop through the stream
while (true)
{
// Get the next packet (if any)
if (GetNextPacket() < 0)
// Break loop when no more packets found
break;
// Video packet
if (packet.stream_index == videoStream)
{
// Check if the AVFrame is finished and set it
if (GetAVFrame())
{
// Update PTS / Frame Offset (if any)
UpdatePTSOffset(true);
// Get PTS of this packet
int pts = GetVideoPTS();
// Apply PTS offset
pts += video_pts_offset;
// Get the video packet start time (in seconds)
double video_seconds = double(pts) * info.video_timebase.ToDouble();
// Increment the correct counter
if (video_seconds <= 1.0)
first_second_counter++;
else if (video_seconds > 1.0 && video_seconds <= 2.0)
second_second_counter++;
else if (video_seconds > 2.0 && video_seconds <= 3.0)
third_second_counter++;
else if (video_seconds > 3.0 && video_seconds <= 4.0)
forth_second_counter++;
else if (video_seconds > 4.0 && video_seconds <= 5.0)
fifth_second_counter++;
else
// Too far
break;
}
}
}
// cout << "FIRST SECOND: " << first_second_counter << endl;
// cout << "SECOND SECOND: " << second_second_counter << endl;
// cout << "THIRD SECOND: " << third_second_counter << endl;
// cout << "FORTH SECOND: " << forth_second_counter << endl;
// cout << "FIFTH SECOND: " << fifth_second_counter << endl;
int sum_fps = first_second_counter + second_second_counter + third_second_counter + forth_second_counter + fifth_second_counter;
int avg_fps = round(sum_fps / 5.0f);
// 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)
{
// Update FPS for this reader instance
info.fps = Fraction(avg_fps, 1);
cout << "UPDATED FPS FROM " << fps << " to " << info.fps.ToDouble() << endl;
}
// Seek to frame 1
Seek(1);
}