Comments on: FFmpeg x264 encoding guide http://rob.opendot.cl stuff about me, what i do and some other hopefully useful stuff Sun, 05 Sep 2010 15:01:25 +0000 hourly 1 http://wordpress.org/?v=3.0.1 By: Media formats... Encoding... Decoding... etc... http://rob.opendot.cl/index.php/useful-stuff/ffmpeg-x264-encoding-guide/comment-page-2/#comment-15052 Media formats... Encoding... Decoding... etc... Sun, 05 Sep 2010 15:01:25 +0000 http://rob.opendot.cl/index.php/ffmpeg-x264-encoding-guide/#comment-15052 [...] for i in *; do ffmpeg -i "$i" -acodec libfaac -ab 96k -vcodec libx264 -vpre normal -crf 22 -threads 2 "${i%.*}.mp4";done More info on h264 encoding with ffmpeg http://rob.opendot.cl/index.php/usef...ncoding-guide/ [...] [...] for i in *; do ffmpeg -i "$i" -acodec libfaac -ab 96k -vcodec libx264 -vpre normal -crf 22 -threads 2 "${i%.*}.mp4";done More info on h264 encoding with ffmpeg http://rob.opendot.cl/index.php/usef…ncoding-guide/ [...]

]]> By: rob http://rob.opendot.cl/index.php/useful-stuff/ffmpeg-x264-encoding-guide/comment-page-2/#comment-15051 rob Wed, 01 Sep 2010 16:31:15 +0000 http://rob.opendot.cl/index.php/ffmpeg-x264-encoding-guide/#comment-15051 The presets don't constrain the H.264 Profile, except for the main and baseline presets. Unless you're specifying the main or baseline presets, you're using High Profile. The level is dependent on the resolution, frame rate and bit rate. See <a href="http://rob.opendot.cl/index.php/useful-stuff/h264-profiles-and-levels/" rel="nofollow">here</a> for more details. It's not so easy to find out what the level is after you've encoded a file, but you can apply restrictions and set the level at encode-time using the -bufsize -maxrate and -level options. The presets don’t constrain the H.264 Profile, except for the main and baseline presets. Unless you’re specifying the main or baseline presets, you’re using High Profile. The level is dependent on the resolution, frame rate and bit rate. See here for more details.

It’s not so easy to find out what the level is after you’ve encoded a file, but you can apply restrictions and set the level at encode-time using the -bufsize -maxrate and -level options.

]]> By: keith http://rob.opendot.cl/index.php/useful-stuff/ffmpeg-x264-encoding-guide/comment-page-2/#comment-15050 keith Wed, 01 Sep 2010 14:29:07 +0000 http://rob.opendot.cl/index.php/ffmpeg-x264-encoding-guide/#comment-15050 Thanks for the great guide Rob! I was wondering if you could explain how the different presets correspond with the MIME types which should be used for the generated videos. It looks like there are two parts to the video component of the complete MIME type: profile and AVC level (http://wiki.whatwg.org/wiki/Video_type_parameters). If I am using the "hq" preset to encode a video, does that correspond to the H.64 "High" profile? How do I determine what the AVC level is? Any insight would be greatly appreciated. Thanks :) Thanks for the great guide Rob!

I was wondering if you could explain how the different presets correspond with the MIME types which should be used for the generated videos. It looks like there are two parts to the video component of the complete MIME type: profile and AVC level (http://wiki.whatwg.org/wiki/Video_type_parameters).

If I am using the “hq” preset to encode a video, does that correspond to the H.64 “High” profile? How do I determine what the AVC level is?

Any insight would be greatly appreciated.

Thanks :)

]]> By: rob http://rob.opendot.cl/index.php/useful-stuff/ffmpeg-x264-encoding-guide/comment-page-2/#comment-15047 rob Mon, 23 Aug 2010 06:16:13 +0000 http://rob.opendot.cl/index.php/ffmpeg-x264-encoding-guide/#comment-15047 Well the command line looks OK, but add '-threads 0' to use libx264 in multi-threaded mode so it can capitalise on the cores you have. Depending on your system and what else the system is doing, it may well be that the encoding can't keep up. Ideally you would want to 'dump' the rtp streams to a file without transcoding while you're capturing and then transcode later. But if you have to transcode on-the-fly and -threads 0 doesn't solve it, try a faster preset. And you probably want to use a higher bitrate for the video, perhaps try something around ~250kbps and see if that's good enough quality. Well the command line looks OK, but add ‘-threads 0′ to use libx264 in multi-threaded mode so it can capitalise on the cores you have. Depending on your system and what else the system is doing, it may well be that the encoding can’t keep up.

Ideally you would want to ‘dump’ the rtp streams to a file without transcoding while you’re capturing and then transcode later. But if you have to transcode on-the-fly and -threads 0 doesn’t solve it, try a faster preset. And you probably want to use a higher bitrate for the video, perhaps try something around ~250kbps and see if that’s good enough quality.

]]> By: Suman Ramineni http://rob.opendot.cl/index.php/useful-stuff/ffmpeg-x264-encoding-guide/comment-page-2/#comment-15045 Suman Ramineni Fri, 20 Aug 2010 20:23:28 +0000 http://rob.opendot.cl/index.php/ffmpeg-x264-encoding-guide/#comment-15045 Hi Rob, I have found out a solution for my streaming problem. Now I'm actually able to catch the webcam stream using ffmpeg on the server and save the output .ts fil. Here is the modified command that worked for me ffmpeg -i rtp://174.121.223.170?localport=1234 -acodec libfaac -ar 48000 -ab 64k -vcodec libx264 -vpre slow -b 128k -s 320×240 -f mpegts output.ts However,the quality of the output .ts file is pretty bad. I can hardly see my webcam stream playing. Can you please suggest me the bitrates and other values that are to be used for better quality of the picture? Thanks, Suman.R Hi Rob,
I have found out a solution for my streaming problem. Now I’m actually able to catch the webcam stream using ffmpeg on the server and save the output .ts fil. Here is the modified command that worked for me
ffmpeg -i rtp://174.121.223.170?localport=1234 -acodec libfaac -ar 48000 -ab 64k -vcodec libx264 -vpre slow -b 128k -s 320×240 -f mpegts output.ts
However,the quality of the output .ts file is pretty bad. I can hardly see my webcam stream playing. Can you please suggest me the bitrates and other values that are to be used for better quality of the picture?
Thanks,
Suman.R

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