Texas Instruments DM365, User Manual

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API Reference
4-46
and
intraFrameInterval
= 30. This means that at every 30
th
frame, there will be an I frame. But at every 300
th
frame, an IDR
frame will be placed instead of I frame. IDR frame is used for
synchronization.
‰ The MV and SAD is dumped in the
outBuf
. The extra buffer is
requested during
XDM_GETBUFINFO
call. If multiple slice is on, then
MV-SAD information is in the index 2 of the buffers pointed by
XDM_BufDesc *outBufs
and index 1 is for packet size information.
If multiple slice is off, the MV-SAD is dumped in index 1 of buffer
pointers. Index 0 is always used for bit-stream data. MV SAD
information is in the following format:
‰ Word0: MVy[bit 31-16]:MVx[bit 15-0]
‰ Word1: SAD [bit 31-0]
For motion vector and SAD, the top left partition is used in case
multiple MV is enabled.
‰ Regions where the viewer pays more attention to are called regions
of interest (ROI). In such scenarios it is important that the ROI areas
are reproduced as reliable as possible since they contribute
significantly towards the overall quality and perception of the video.
This is achieved by assigning higher number of bits to the ROI areas
when compared to non-ROI areas.
‰ If the current frame at low resolution encoder is encoded as IDR/I
frame then no scene change information is passed to high resolution
encoder.
‰ Forcing intra MBs when
airRate
>0 is done as explained below.
Randomized AIR is used as intra refresh startegy. In this case
atlease
airRate
number of MBs in a frame will be set as intra,
except for the last module. There could be more than
airRate
MBs
as intra because there could be macroblocks coded as intra due to
intra/inter mode decision.
Consider that there are 396 MBs in a frame and airRate = 10. So
after 39 frames 390 MBs will be refreshed. So for 40
th
frame only 6
MBs get refreshed ti intra. So for all frames atlease airRate number
of MBs in a frame will not be Intra.
For
encQuality
= 0, when AIR is ON, contrained intra prediction
gets used. In other modes of operation, contrained intra prediction is
not used when AIR is ON.
‰ If
sliceMode
= 0 then
sliceSize
value is ignored. Entire frame will
be encoded as a single slice.
‰
SliceMode
= 1 is Reserved
‰
If SliceMode = 2 then sliceSize indicates:
Size of each slice in number of MBs.
•
0 – Single Slice per Frame
•
>0 – Multiple Slices with each slice having MBs <= sliceSize.
Default value = 0
This feature is only present when
encQuality = 0 .
Slicesize value should be multiple of 2 always. Value of slice size is limited
by total number of MBs in frame.
In case of inputs having odd multiple of MBs in a row, an virtual MB