// method 1: add preview as separate track with slightly bigger resolution (via Pituz)
static void GeneratePreview(string filePath)
{
OutputProcessor sp = new SimpleProcessor();
ProcessingUnit pu = sp.CreateOne();
string fileName = Path.GetFileName(filePath),
output = filePath.Substring(0, filePath.LastIndexOf('.') + 1) + "preview.webm",
previewSource = ArgList.Get(Arg.PREVIEW_SOURCE) ? GetFullPath(ArgList.Get(Arg.PREVIEW_SOURCE).AsString()) : filePath,
previewTiming = ArgList.Get(Arg.PREVIEW).AsString();
// Preview
long time = DateTime.Now.ToFileTimeUtc();
string previewWebm = GetFolder(filePath) + "\\preview_" + time.ToString() + ".webm";
// Same scale
Ffprober.Result result = Ffprober.Probe(filePath);
string scale = result.Scale;
scale = scale == null ? string.Empty : $",scale={result.WidthPix + 1}:-1";
scale = $"-filter:v:1 \"trim=end_frame=2{scale}\"";
string args = $"-hide_banner -i \"{filePath}\" -ss {previewTiming} -i \"{previewSource}\" -c copy -map 0:v -map 0:a -map 1:v -c:v:1 vp9 -b:v:1 0 -crf 8 -speed 1 {scale} \"{output}\"";
ExecuteFFMPEG(args, pu);
sp.Destroy(pu);
}
static void GeneratePreviewOld(string filePath)
{
OutputProcessor sp = new SimpleProcessor();
ProcessingUnit pu = sp.CreateOne();
string fileName = Path.GetFileName(filePath),
output = filePath.Substring(0, filePath.LastIndexOf('.') + 1) + "preview.webm",
previewSource = ArgList.Get(Arg.PREVIEW_SOURCE) ? GetFullPath(ArgList.Get(Arg.PREVIEW_SOURCE).AsString()) : filePath,
previewTiming = ArgList.Get(Arg.PREVIEW).AsString();
// Preview
long time = DateTime.Now.ToFileTimeUtc();
string previewWebm = GetFolder(filePath) + "\\preview_" + time.ToString() + ".webm";
// Same scale
Ffprober.Result result = Ffprober.Probe(filePath);
string scale = result.Scale;
scale = scale == null ? string.Empty : (",scale=" + scale);
scale = $"-vf \"trim=end_frame=2{scale}\"";
string args = $"-hide_banner -ss {previewTiming} -i \"{previewSource}\" -c:v vp9 -pix_fmt +yuv420p -b:v 0 -crf 8 -speed 1 -an -sn {scale} \"{previewWebm}\"";
ExecuteFFMPEG(args, pu);
// Bad muxing fix
string videoOnly = $"video_{time}.webm";
args = $"-hide_banner -i \"{filePath}\" -c copy -map 0:v \"{videoOnly}\"";
ExecuteFFMPEG(args, pu);
// Concat
string concatedWebm = $"concat_{time}.webm";
string concatFile = $"concat_{time}.txt";
File.WriteAllText(concatFile, $"file '{previewWebm}'\r\nfile '{videoOnly}'", Encoding.Default);
string fps = result.Framerate;
string dur = Ffprober.Probe(previewWebm).EndTime;
if (dur == null)
{
dur = "0.042";
}
args = $"-hide_banner -f concat -i \"{concatFile}\" -c copy \"{concatedWebm}\"";
ExecuteFFMPEG(args, pu);
args = $"-hide_banner -y -itsoffset 0.5 -i \"{filePath}\" -i \"{concatedWebm}\" -map 1:v -map 0:a -c copy \"{output}\"";
ExecuteFFMPEG(args, pu);
// Delete
File.Delete(concatFile);
File.Delete(previewWebm);
File.Delete(concatedWebm);
File.Delete(videoOnly);
sp.Destroy(pu);
}