View Issue Details
| ID | Project | Category | View Status | Date Submitted | Last Update |
|---|---|---|---|---|---|
| 0000203 | JVT JM H.264/AVC reference software | encoder and decoder | public | 2010-02-08 23:27 | 2013-06-11 20:40 |
| Reporter | Ismaeil | Assigned To | Alexis Michael Tourapis | ||
| Priority | normal | Severity | major | Reproducibility | always |
| Status | assigned | Resolution | open | ||
| Product Version | JM 16.2 | ||||
| Summary | 0000203: 4:2:2/4:4:4 chroma Intra DC prediction bug when constraint intra pred is enabled | ||||
| Description | I believe the bug is in both encoder and decoder. The computation of chroma DC prediction in 4:2:2 and 4:4:4 mode when constrained_intra_pred_flag=1 is incorrect. Specifically in intra_chroma_pred.c (of the decoder), in function Intrapred_chroma, the Left_avail flag used for computing both BOTTOM LEFT/RIGHT (line 153 and 156) is incorrectly used for 422/422. The current code uses left_avail[1] which is correct for 420 but not for 422 and 444. For 422 it should be left_avail[0] for 4x4blocks 2 and 3 of 8x8block0 [b8=0] and left_avail[1] for all 4 4x4blocks of 8x8block1 [b8=1]. Chroma 444 should have the same problem. | ||||
| Tags | chroma, dc, intra | ||||
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The fix for jm18.4 version is attached. Please, use it until the official fix comes. |
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Acknowledged and fixed for an upcoming release. |
| Date Modified | Username | Field | Change |
|---|---|---|---|
| 2010-02-08 23:27 | Ismaeil | New Issue | |
| 2012-12-06 03:32 | Victor | Tag Attached: chroma | |
| 2012-12-06 03:32 | Victor | Tag Attached: dc | |
| 2012-12-06 03:32 | Victor | Tag Attached: intra | |
| 2012-12-06 03:39 | Victor | File Added: jm18.4.chroma_fix.zip | |
| 2012-12-06 03:41 | Victor | Note Added: 0000561 | |
| 2013-06-11 20:39 | Alexis Michael Tourapis | Note Added: 0000577 | |
| 2013-06-11 20:40 | Alexis Michael Tourapis | Assigned To | => Alexis Michael Tourapis |
| 2013-06-11 20:40 | Alexis Michael Tourapis | Status | new => assigned |
