I have used several rendering apps including handbrake which has a specific web optimized check box.

Videos I have rendered with that checked, I dont get the youtube warning recommendation for optimizing streaming (which youtube then does anyway if your upload is not web optimized)

So If I render to h264 in kdenlive, what custom parameter would be used to optimize for web streaming?

qt-faststart, an ffmpeg and x264 option but not sure if it's available via MLT kdenlives underlying media handling tool.

Kind of surprised this is not handled by ffmpeg with an option.

http://superuser.com/questions/438390/creatingmp4-videos-ready-forhttp-streaming

looks to be 3 tools to do this from commandline.
from that post says this.

QTIndexSwapper, an Adobe AIR application

MP4Box, free and open source, running a command similar to the following, where you can change the interval (here, 500):

mp4box -inter 500 input.mp4

qt-faststart in Python, which works everywhere where Python is installed.

qtfaststart input.mp4

ffmpeg does handle it I think: -movflags +faststart

I will try that thanks.

How would that line fit into the arguments window for kdenlive?

everything I see there says something=something
like

vb=4000k, etc...

Same as ffmpeg command line I guess. Faststart is an option for MLT.

http://www.mltframework.org/bin/view/MLT/ConsumerAvformat#movflags_AN3

So perhaps check some of the render profiles for media devices already in kdenlive, it may already be being used in one of them

believe me I am like a computer so need very exact instructions, LOL.

For example, this is how kdenlive diplays ffmpeg arguments in the gui custom window

f=mp4 hq=1 acodec=aac ab=%audiobitrate+'k' ar=48000 pix_fmt=yuv420p vcodec=libx264 minrate=0 vb=%bitrate+'k' g=250 bf=3 b_strategy=1 subcmp=2 cmp=2 coder=1 flags=+loop flags2=dct8x8 qmax=51 subq=7 qmin=10 qcomp=0.6 qdiff=4 trellis=1 aspect=%dar pass=%passes


This one is using the h264 mp4.
So what would you put in there?

movflags=faststart ?

Add it and try it. :-) I'd have to do the same.

I was wondering about this myself just recently - since youtube is offering faststart up as a hint on how to optimise for web streaming I guess this is not much of a co-incidence.

I have put up two vidoes that differ just by the addition of the movflags=faststart parameter to the H.264 file rendering profile. They are very short clips so this might be why. But I can't really see any difference in them. In fact when I first loaded them up the files were the same lenght and from the same part of the orignal clip and youtube flagged them as being identicle. I had to render different parts of the original to get them both on youtube.

http://www.youtube.com/watch?v=VAmk-MGltsg - no fast start
http://www.youtube.com/watch?v=Sj8xIBySjXs - with fast start

the render profile is

f=mp4 hq=1 acodec=aac ab=%audiobitrate+'k' ar=48000 pix_fmt=yuv420p vcodec=libx264 minrate=0 vb=%bitrate+'k' g=250 bf=3 b_strategy=1 subcmp=2 cmp=2 coder=1 flags=+loop flags2=dct8x8 qmax=51 subq=7 qmin=10 qcomp=0.6 qdiff=4 trellis=1 aspect=%dar pass=%passes movflags=faststart

Who knows if this is making a difference but the render profile did not fail.

Youtube will modify the metadata even if you dont.
I think they want you to do it first because it saves them a little processing power.
They do all sorts of stuff to the video to make the user experience work. On a large file, it takes hours to get everything done. Metadata, remove the shakes, uploads.

The idea of faststart is that it's a progressive download over http protocol, so movie starts playing before the whole file is downloaded, which is supposedly good for longer videos or those of higher bitrate however on long videos this can cause buffering problems vs a streaming server via MMS or RTSP at the other end and a decent internet connection.

Short videos are probably going to see no difference. Although I notice a difference between faststart and no faststart on a typical 5 - 10mins higher bitrate via AppleTV 3 from Vimeo for example.

http://www.streamingmedia.com/Articles/Editorial/What-Is-.../What-Is-a-Streaming-Media-Protocol-84496.aspx

ok, i tested out the 2 profiles. one being (without quickstart)

Code: Select all

f=mp4 hq=1 acodec=aac ab=%audiobitrate+'k' ar=48000 pix_fmt=yuv420p vcodec=libx264 minrate=0 vb=%bitrate+'k' g=250 bf=3 b_strategy=1 subcmp=2 cmp=2 coder=1 flags=+loop flags2=dct8x8 qmax=51 subq=7 qmin=10 qcomp=0.6 qdiff=4 trellis=1 aspect=%dar pass=%passes

and this one (with quickstart)

Code: Select all

f=mp4 hq=1 acodec=aac ab=%audiobitrate+'k' ar=48000 pix_fmt=yuv420p vcodec=libx264 minrate=0 vb=%bitrate+'k' g=250 bf=3 b_strategy=1 subcmp=2 cmp=2 coder=1 flags=+loop flags2=dct8x8 qmax=51 subq=7 qmin=10 qcomp=0.6 qdiff=4 trellis=1 aspect=%dar pass=%passes movflags=faststart

and believe it or not when I watched the videos for the first time on youtube the video that actually had the faststart enabled stopped buffering the video around the 55 second mark and then continued slowly buffering as it started playing whereas the video that just used the default h.264 encoding profile actually buffered all the way fully to the end while the video started playing.

So this is really weird. Both times youtube warned me that I could make processing the video quicker if i enabled quickstart but they both uploaded and processed in the same amount of time.