Erroneous video output from mvp using VAAPI hardware decoding

I own a laptop with Intel HD graphics (i915 kernel driver) and I'm trying to get hardware-accelerated video playback under Debian Jessie. I have installed i965-va-driver and libva-intel-vaapi-driver packages, and vainfo gives me a list of supported codecs: $ vainfo libva info: VA-API version 0.36.0 libva info: va_getDriverName() returns 0 libva info: Trying to open /usr/lib/i386-linux-gnu/dri/i965_drv_video.so libva info: Found init function __vaDriverInit_0_36 libva info: va_openDriver() returns 0 vainfo: VA-API version: 0.36 (libva 1.4.1) vainfo: Driver version: Intel i965 driver for Intel(R) CherryView - 1.4.1 vainfo: Supported profile and entrypoints VAProfileMPEG2Simple : VAEntrypointVLD VAProfileMPEG2Simple : VAEntrypointEncSlice VAProfileMPEG2Main : VAEntrypointVLD VAProfileMPEG2Main : VAEntrypointEncSlice ... Yet when I try to play a video with mpv --hwdec=vaapi filename, I get a totally broken video output: Now, the picture does change with the rhythm which matches the audio, suggesting the decoding does happen, but the result is completely unusable. Does anyone happen to have experience with accelerated video on Intel hardware? Any ideas of what I could be doing wrong? Here's what my /var/log/Xorg.0.log says: [ 11.754] (II) intel(0): SNA initialized with Cherryview (gen8) backend [ 11.755] (==) intel(0): Backing store enabled [ 11.755] (==) intel(0): Silken mouse enabled [ 11.755] (II) intel(0): HW Cursor enabled [ 11.755] (II) intel(0): RandR 1.2 enabled, ignore the following RandR disabled message. [ 11.756] (==) intel(0): DPMS enabled [ 11.757] (==) intel(0): Display hotplug detection enabled [ 11.757] (II) intel(0): [DRI2] Setup complete [ 11.757] (II) intel(0): [DRI2] DRI driver: i965 [ 11.757] (II) intel(0): [DRI2] VDPAU driver: va_gl [ 11.757] (II) intel(0): direct rendering: DRI2 enabled [ 11.757] (II) intel(0): hardware support for Present enabled