Documentation

acl.himpi.vdec_get_frame

C Prototype

hi_s32 hi_mpi_vdec_get_frame(hi_vdec_chn chn, hi_video_frame_info *frame_info, hi_vdec_supplement_info *supplement, hi_vdec_stream *stream, hi_s32 milli_sec);

Python Function

frame_info, supplement, stream, ret = acl.himpi.vdec_get_frame(chn, milli_sec)

Function Usage

Fetches the decoded image and input stream of a decoding channel.

During JPEGD image decoding, if hardware decoding fails when this API is called, software decoding is triggered within this API.

The Atlas 200/300/500 Inference Product does not support this API in the current version.

The Atlas Training Series Product does not support this API in the current version.

Input Description
chn: int, decoding channel ID.
milli_sec: int, timeout interval (ms).
  • -1: blocking mode.
  • 0: non-blocking mode.
  • > 0: timeout interval (timeout mode). The timeout interval varies with the operating system. The deviation is generally within a time slice of an operating system. For example, if the time slice of an operating system is 4 ms and the value of milli_sec is set to 1, the actual timeout interval ranges from 1 ms to 5 ms. When the CPU load is high, the timeout interval may still fluctuate.
NOTE:

In the JPEGD image decoding scenario, the timeout interval configured here refers only to the wait time for obtaining the hardware decoding result, excluding the software decoding time.

Return Value
ret: int, error code.
  • 0: success. After the decoded data is obtained successfully, acl.himpi.vdec_release_frame needs to be called to release decoding resources. Although success message is returned, the fetched data may be the result of decoding failure. To check the decode success or failure result, query the frame_flag parameter of hi_video_frame (a member of hi_video_frame_info).
  • Other values: failure. For details, see VDEC/JPEGD Return Codes.
    NOTE:
    • If no channel is created during image decoding, the error code HI_ERR_VDEC_UNEXIST is returned.
    • If the channel is destroyed in the image fetching process, the error code HI_ERR_VDEC_UNEXIST is returned.
    • If the channel is reset in the image fetching process, the error code HI_ERR_VDEC_UNEXIST is returned.
    • In non-blocking mode, if the buffer has no decoded images, the error code HI_ERR_VDEC_BUF_EMPTY is returned.
    • In timeout mode, if no hardware decoding result is obtained within the specified timeout interval, the error code HI_ERR_VDEC_BUF_EMPTY is returned. In this case, increase the timeout interval or call this API repeatedly to obtain the decoding result.

stream: dict, pointer to information dictionary of decoded input streams. For details, see hi_vdec_stream.

frame_info: dict, pointer to information about decoded images. The decoded data is stored in the device memory. For details, see hi_video_frame_info.

supplement: dict, supplementary information about the decoded images. This parameter is reserved.

Restrictions
  • This API fetches the VDEC result, including the input buffer and output buffer.
  • For decoding of JPEG(420), JPEG(422), or JPEG(440) input images, if the input width and height are odd numbers, the output width and height are rounded down to the nearest multiples of 2 by default. For decoding of JPEG(444) or JPEG(400) input images, the output width and height are consistent with the input width and height by default. To adjust the width and height alignment mode of the output image, call acl.himpi.vdec_set_jpegd_precision_mode.
Parent topic: VDEC/JPEGD APIs