Decoder Class

Decoder Class#

Instantiation#

To instantiate a decoder instance, pass the following parameters:

  • device_id: The GPU device ID, default is 0

  • mem_type: The mem type of output surface - 0: Internal 1: dev_copied 2: host_copied, default is 1

  • codec: The codec ID obtained by GetRocDecCodecID API

  • b_force_zero_latency: Force zero latency flag, default is ‘False’

  • crop_rect: See Structures Classess, optional, default: ‘None’, no cropping

  • max_width: Max width, default is 0

  • max_height: Max height, default is 0

  • clk_rate: Clock rate, default is 1000

Example:#

# create decoder instance
viddec = dec.decoder(device_id, mem_type, codec_id, b_force_zero_latency, crop_rect, 0, 0, 1000)

Member functions#

The following are the member functions of the Decode class.

DecodeFrame(packet)#

Decodes video frames described by the input Packet structure obtained from demux functions. Returns the count of decoded frames.

GetFrame(packet)#

Obtains a pointer to the current decoded frame in the input packet. Returns the current frame time stamp, the frame pointer, and the time stamp saved in the packet.

Example:#

# decoding loop
while True:
        packet = demuxer.DemuxFrame()

        n_frame_returned = viddec.DecodeFrame(packet)

        for i in range(n_frame_returned):
                viddec.GetFrame(packet)

        # TO DO: process the frame or save it, etc.
        # ...

        # release frame
        viddec.ReleaseFrame(packet)

        if (packet.frame_size <= 0):  # EOF: no more to decode
                break

GetFrameRgb(packet, rgb_format)#

Obtains a pointer to the current decoded frame in the input packet, and converts that YUV frame to ‘Tensor’ in RGB format. Returns the current frame time stamp, the frame pointer, and the time stamp saved in the packet.

  • packet: The demuxed packet contains the demuxed frames information, and the desired rgb format

  • rgb_format: 1 for bgr, 3 for rgb

GetFrameSize()#

Returns the size of the current decoded frame in bytes.

GetGpuInfo()#

Returns the ConfigInfo structure for the current GPU device

Example:#

# Get GPU device information
cfg = viddec.GetGpuInfo()

# print GPU info out
print("GPU device " + str(device_id) + " \- " + cfg.device_name + "[" + cfg.gcn_arch_name + "] on PCI bus " + str(cfg.pci_bus_id) + ":" + str(cfg.pci_domain_id) + "." + str(cfg.pci_device_id))

GetHeight()#

Returns the height of the current decoded frame.

GetOutputSurfaceInfo()#

Returns the current decoded frame’s surface information structure pointer.

GetResizedOutputSurfaceInfo()#

Returns the current decoded and resized frame’s surface information structure pointer.

GetStride()#

Returns the stride of the current decoded frame.

GetWidth()#

Returns the width of the current decoded frame.

ResizeFrame(packet, resize_dim, surface_info)#

Resizes the decode frame pointed to by the passed packet, see: Structures Classess, to the new dimension in resize_dim, to the new dimension using the passed surface info.

  • packet: The demuxed packet contains the demuxed frames information, and the desired rgb format

  • resize_dim: The new dimension, width and height

  • surface_info: The current surface info obtained by GetOutputSurfaceInfo API

Example:#

# resize frame to new dimension
resize__dim = [1024, 720]

surface__info = viddec.GetOutputSurfaceInfo()

frame_is_resized = False

if(viddec.ResizeFrame(packet, resize_dim, surface_info) != 0):
        frame_is_resized = True

SaveFrameToFile(output_file_path, frame_adrs, surface_info)#

Saves all the decoded frames to a disk file in YUV format.

  • output_file_path: The full path disk file name to save the YUV frames

  • frame_adrs: The current frame pointer, obtained from the used packet

  • surface_info: The current decode frame surface information structure pointer

SaveTensorToFile(output_file_path, frame_adrs, width, height, rgb_format, surface_info)#

Saves all the decoded frames after being converted to a Tensor to a disk file in RGB format.

  • output_file_path: The full path disk file name to save the YUV frames

  • frame_adrs: The current frame/tensor pointer, obtained from the used packet

  • width: The width of the current Tensor

  • height: The height of the current Tensor

  • rgb_format: 1 for bgr, 3 for rgb

  • surface_info: The current decode frame surface information structure pointer

ReleaseFrame(packet)#

Release the GPU memory of the current decoded frame.

GetNumOfFlushedFrames()#

Returns the count of the flushed frames.

Example:#

# beyond the decoding loop
n_frame += viddec.GetNumOfFlushedFrames()

InitMd5()#

Initialize the process to obtain the MD5 of the decoded frames.

Example:#

# init MD5
viddec.InitMd5()

UpdateMd5ForFrame(frame_adrs, surface_info)#

Update the MD5 calculation with the current decoded frame.

  • frame_adrs: The current frame/tensor pointer, obtained from the used packet

  • surface_info: The current decode frame surface information structure pointer

Example:#

# update MD5 with current decoded frame
surface_info = viddec.GetOutputSurfaceInfo()
viddec.UpdateMd5ForFrame(packet.frame_adrs, surface_info)

FinalizeMd5()#

Ends the MD5 process and returns the digest 16 character.

Example:#

# finalize and print MD5 check
digest = viddec.FinalizeMd5()

print("MD5 message digest: ", end=" ")
str_digest = ""
for i in range(16):
        str_digest = str_digest + str(format('%02x' % int(digest[i])))

print(str_digest)

SetReconfigParams(flush_mode, out_file_name)#

Specify the flush mode and the output file name to use in multi resolution video support.

  • flush_mode:

    • 0: Just flush to get the frame count

    • 1: The remaining frames will be dumped to file in this mode

    • 2: Calculate the MD5 of the flushed frames

  • out_file_name: The full path disk file name to save the YUV frames

Example:#

# set reconfiguration params based on user arguments
flush_mode = 0

if (output_file_path is not None):
        flush_mode = 1
elif b_generate_md5:
        flush_mode = 2

viddec.SetReconfigParams(flush_mode, output_file_path if (output_file_path is not None) else str(""))
Contents