View source for TPESystem/Media/DevicePortingIssues

==TPESystem/Media/DevicePortingIssues==
Device porting issues of media playback on Firefox OS

===Problems And Solutions===
We've encountered some similar media playback issues while porting different devices. The following list contains some common problems we've found and our current solutions as well:
# '''Problem: I cannot playback video files with large resolution.'''
#* Solution: Make sure '''''ro.moz.omx.hw.max_width''''' & '''''ro.moz.omx.hw.max_height''''' values are suitable for video decoding on the target device.
#* Reference: {{bug|819609}} and {{bug|911113}}
#** Each time one video clip is going to be played, ''OMXCodecProxy'' is used to handle resource management of hardware video decoders.
#** After one video ''OMXCodec'' has been created successfully, ''OMXCodecProxy'' will double check the product of these two values with the actual video resolution.
#** If the video resolution is bigger than the product of these two values, ''OMXCodecProxy'' will destroy this newly created ''OMXCodec''. As a result, the playback of this video clip will be abandoned in this case.
# '''Problem: I cannot generate thumbnails of my video files in the video application.'''
#* Solution: Check the color format enum definition, '''''HAL_PIXEL_FORMAT_XXX''''', to see if '''''GrallocImage::GetAsSurface()''''' can handle color format conversion correctly.
#* Reference: {{bug|891274}} and {{bug|931733}}
#** Currently ''HAL_PIXEL_FORMAT_XXX'' is hardcoded in GrallocImages.h.
#** The way how ''HAL_PIXEL_FORMAT_XXX'' should be ported in Firefox OS will be improved in the near future.
# '''Problem: I always encounter OMXCodec::waitForBufferFilled_l() timeout with ''"Timed out waiting for output buffers: 0/xxx"'' message while playing some specific video files (usually mp4 files.)'''
#* Solution: Make sure all the buffers allocated from '''''ANativeWindows''''' can be used for video decoding.
#* Reference: {{attachment|744257}} on {{bug|864230}}
#** In AOSP, ANativeWindow is used as a buffer source and also as a render target. ANativeWindow needs to keep at least ''minUndequeuedBufs'' while rendering video. Although some number of buffers have to be kept in ANativeWindow, every buffer in the buffer queue can takes turns to be filled, be rendered, and be emptied. So utilization of buffers in the queue is ok.
#** In Firefox OS, ANativeWindow is used as a buffer source, but not as a render target. If we keep ''minUndequeuedBufs'' buffers in ANativeWindow, these buffers will always be kept in ANativeWindow and never have chances to be filled. As a result, it's very easy to encounter buffer starvation during video decoding.
# '''Problem: I cannot resume playback by clicking the play button after the video/audio has been paused.'''
#* Solution: Make sure to return '''''ERROR_UNSUPPORTED''''' in '''''OMXCodec::pause()''''' if underlying OMX IL component doesn't support pause and resume function.
#* Reference: {{attachment|8340486}} on {{bug|919590}}
#** This solution is not yet ''review+'', but this is the suggested solution based on the discussion on bugzilla.