Bug 349688

Seeking in the timeline isvery, very slow - 5-15 seconds delay between clicking in the timeline and the cursor moving. When I can eventually start video playback, it appears to be completely unresponsive - no amount of hitting the spacebar or swearing at the computer will stop the video :)
Editing is simply not possible.





Reproducible: Always

Steps to Reproduce:
1. Open project, click in timeline
2. wait 15 seconds.
3. cursor appears at desired location.
4. hit play - video starts playing.
5. desperately try to stop playback using the spacebar and previously mentioned foul language.

Actual Results:  
30 seconds later, the video might stop. Maybe. Or it might pause before beginning to play again (a severely delayed reaction to an earlier use of the spacebar).

Expected Results:  
seeking, playback and stopping should happen in realtime.

Problem occurs with H264 AVCHD (Canon 5DmkII files) and when using proxies. 
Problem occurs on 15.04.03 (from kubuntu-ci) and 15.04.02 (from sunab) but not Dan's daily build (from 2015-06-22). Playback is also totally fine with Shotcut, for example.

Ubuntu 15.04
Lenovo s440 
Intel® Core™ i7-4500U CPU @ 1.80GHz × 4 
Memory: 7,5 GiB

Graphics:
00:02.0 VGA compatible controller [0300]: Intel Corporation Haswell-ULT Integrated Graphics Controller [8086:0a16] (rev 09) (prog-if 00 [VGA controller])
	Subsystem: Lenovo Device [17aa:501d]
	Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+
	Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 0
	Interrupt: pin A routed to IRQ 44
	Region 0: Memory at f0000000 (64-bit, non-prefetchable) [size=4M]
	Region 2: Memory at e0000000 (64-bit, prefetchable) [size=256M]
	Region 4: I/O ports at 6000 [size=64]
	Expansion ROM at <unassigned> [disabled]
	Capabilities: <access denied>
	Kernel driver in use: i915

06:00.0 Display controller [0380]: Advanced Micro Devices, Inc. [AMD/ATI] Sun XT [Radeon HD 8670A/8670M/8690M] [1002:6660] (rev ff) (prog-if ff)
	!!! Unknown header type 7f
	Kernel driver in use: radeon

Software versions:

Package: kdenlive
Status: install ok installed
Priority: optional
Section: video
Installed-Size: 7394
Maintainer: Olivier Banus <sunab@free.fr>
Architecture: amd64
Version: 15.04.2-0ubuntu0~sunab~vivid4

Package: melt
Status: install ok installed
Priority: optional
Section: utils
Installed-Size: 99
Maintainer: Olivier Banus <sunab@free.fr>
Architecture: amd64
Source: mlt
Version: 0.9.6-0ubuntu0~sunab~vivid1
Depends: libc6 (>= 2.4), libmlt6 (>= 0.9.6), libmlt-data (>= 0.9.6-0ubuntu0~sunab~vivid1)

Package: ffmpeg
Status: install ok installed
Priority: optional
Section: video
Installed-Size: 1714
Maintainer: Ubuntu Developers <ubuntu-devel-discuss@lists.ubuntu.com>
Architecture: amd64
Multi-Arch: foreign
Version: 7:2.5.7-0ubuntu0.15.04.1