Artifacts During VDEC Video Decoding

Symptom

When the input stream is decoded by VDEC, the obtained decoded data is incorrect, causing artifacts, as shown in Figure 1. The log contains information similar to "decode error", "input stream error, can't decode, report to user", "num_ref_idx_l0_active(30) out of range(0,16)", "dvpp_vdec_vdm_process failed", and "Chan 0 ErrRatio = 44".

Possible Cause

Some frame data in the input stream is incomplete or there are bad frames, causing artifacts during hardware decoding.

Solution

To rectify the fault, perform the following steps:

1. Check the input source stream.

   Use a third-party tool (for example, eseye u) to decode and play the input stream and check whether artifacts occur. If artifacts do not occur, go to Step 2. If artifacts occur, replace the input stream.

2. If the source stream is normal, the stream may be damaged when being transmitted to VDEC on the device. In this case, store the stream transmitted to VDEC by using fwrite() before sending the stream.
   • Use a third-party tool to check the stored stream. If the stream is abnormal, check whether a stream has been sent.
   • Decode the stored stream by using the sample of the corresponding version to check whether the verification stream is normal or whether VDEC supports the format.

     If the sample decoding is normal, it is the development code logic that causes this problem. You can optimize the code logic by referring to the VDEC sample code in sections about media data processing in CANN AscendCL Application Software Development Guide (C&C++).