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View Full Version : Pretranscoding fast, transcoding slow



darkopsy
12-24-2014, 06:57 PM
Hi,
I was wondering if you can help me with this issue. When I start playing a video either through my tv or mezzmo, transcoding on the fly usually works fine but when it's a 1080p video the transcoding speed is around 22fps which is too slow and results in stuttering video. If I choose to pretranscode that video though, I get 40-50fps speed and therefore can start up the video a few seconds after pretranscoding has started to watch it without issues. Why is pretranscoding faster than transcoding?

Here is the ffmpeg output of the video being pretranscoded:
ffmpeg version N-66094-gbb8b752 Copyright (c) 2000-2014 the FFmpeg developers
built on Sep 4 2014 16:23:51 with gcc 4.8.2 (GCC)
configuration: --enable-memalign-hack --arch=x86_64 --target-os=mingw32 --cross-prefix=x86_64-w64-mingw32- --enable-static --disable-shared --enable-zlib --disable-postproc --prefix=/home/peter/ffmpeg/build/gpl64 --enable-libmp3lame --enable-libx264 --enable-gpl --extra-libs='-lx264 -lpthread' --enable-runtime-cpudetect --extra-cflags=-I/home/peter/cc32/include --extra-ldflags=-L/home/peter/cc64/lib --pkg-config=pkg-config --disable-w32threads --enable-libvpx --enable-libvorbis
libavutil 54. 7.100 / 54. 7.100
libavcodec 56. 1.100 / 56. 1.100
libavformat 56. 4.100 / 56. 4.100
libavdevice 56. 0.100 / 56. 0.100
libavfilter 5. 0.103 / 5. 0.103
libswscale 3. 0.100 / 3. 0.100
libswresample 1. 1.100 / 1. 1.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'C:\Users\Darko\Downloads\movies\*':
Metadata:
major_brand : isom
minor_version : 1
compatible_brands: isomavc1
creation_time : 2014-12-19 00:23:17
Duration: 01:36:09.79, start: 0.000000, bitrate: 2136 kb/s
Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709), 1920x1080, 2038 kb/s, 23.98 fps, 23.98 tbr, 24k tbn, 47.95 tbc (default)
Metadata:
creation_time : 2014-12-19 00:23:17
handler_name : video.264#trackID=1:fps=23.976 - Imported with GPAC 0.5.0-rev
Stream #0:1(eng): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 93 kb/s (default)
Metadata:
creation_time : 2014-12-19 00:23:27
handler_name : GPAC ISO Audio Handler

Paul
12-28-2014, 11:40 AM
We'll know why with a set of logs. Turn on logging in Mezzmo (see http://forum.conceiva.com/showthread.php/419-FAQ-How-to-turn-on-diagnostic-logging) and restart your Mezzmo server. Right-click on the video in Mezzmo and click 'Properties'. On the Properties dialog, go to the Transcoding tab and delete all transcoded files. No stream the video to your TV so that the video transcoded\s on-the-fly. Stop your Mezzmo server and exit Mezzmo. Zip up all the logs and email them to us at support [at] conceiva [dot] com. Next, start Mezzmo and delete the transcoded files for the video again. Pre-transcode the video and whilst it is pre-transcoding, right-click on the file in the Transcoding pane and click 'View FFmpeg Output'. Email this to us as well.