Using Video Presets

How to use the Transcoder class to convert a raw YUV video file into a compressed video file. The format of the output is configured with an AVBlocks preset.

The code snippets in this article are from the enc_preset_file sample.

Create a Transcoder object

transcoder = Transcoder()

# Transcoder demo mode must be enabled,
# in order to use the OEM release for testing (without a valid license).
transcoder.allow_demo_mode = True

Configure inputs and outputs

Use the MediaSocket class to configure media sockets and the MediaPin class to configure media pins.

Configure video input

1. Create and configure a VideoStreamInfo object

2. Create a MediaPin object and set the MediaPin.stream_info property.

3. Create a MediaSocket object and add the pin to MediaSocket.pins.

4. Add the socket to Transcoder.inputs.

# Configure input
# The input stream frame rate determines the playback speed
in_stream = VideoStreamInfo()
in_stream.stream_type = StreamType.UncompressedVideo
in_stream.frame_rate = fps
in_stream.frame_width = width
in_stream.frame_height = height
in_stream.color_format = color_id
in_stream.scan_type = ScanType.Progressive

in_pin = MediaPin()
in_pin.stream_info = in_stream

in_socket = MediaSocket()
in_socket.stream_type = StreamType.UncompressedVideo
in_socket.file = input_file
in_socket.pins.add(in_pin)

transcoder.inputs.add(in_socket)

Configure video output

1. Call the MediaSocket.from_preset static method to create a MediaSocket object for a predefined preset

2. Set the MediaSocket.file property to the output filename.

3. Add the socket to Transcoder.outputs.

# Configure output
out_socket = MediaSocket.from_preset(preset_name)
if out_socket is None:
    print(f"Invalid preset: {preset_name}")
    return False

out_socket.file = output_file
transcoder.outputs.add(out_socket)

Run Transcoder

1. Call the Transcoder.open method.

2. Call the Transcoder.run method.

3. Call the Transcoder.close method.

# Open transcoder
if not transcoder.open():
    print_error("Open Transcoder", transcoder.error)
    return False

# Run transcoder
if not transcoder.run():
    print_error("Run Transcoder", transcoder.error)
    transcoder.close()
    return False

transcoder.close()

The complete encode function

def encode(input_file: str, output_file: str, width: int, height: int,
           fps: float, color_id, preset_name: str) -> bool:
    """Encode raw YUV video to compressed video using preset."""
    # Delete output file if it exists
    delete_file(output_file)

    # Create output directory if it doesn't exist
    output_dir = os.path.dirname(output_file)
    if output_dir and not os.path.exists(output_dir):
        os.makedirs(output_dir)

    transcoder = Transcoder()

    # Transcoder demo mode must be enabled,
    # in order to use the OEM release for testing (without a valid license).
    transcoder.allow_demo_mode = True

    # Configure input
    # The input stream frame rate determines the playback speed
    in_stream = VideoStreamInfo()
    in_stream.stream_type = StreamType.UncompressedVideo
    in_stream.frame_rate = fps
    in_stream.frame_width = width
    in_stream.frame_height = height
    in_stream.color_format = color_id
    in_stream.scan_type = ScanType.Progressive

    in_pin = MediaPin()
    in_pin.stream_info = in_stream

    in_socket = MediaSocket()
    in_socket.stream_type = StreamType.UncompressedVideo
    in_socket.file = input_file
    in_socket.pins.add(in_pin)

    transcoder.inputs.add(in_socket)

    # Configure output
    out_socket = MediaSocket.from_preset(preset_name)
    if out_socket is None:
        print(f"Invalid preset: {preset_name}")
        return False

    out_socket.file = output_file
    transcoder.outputs.add(out_socket)

    # Open transcoder
    if not transcoder.open():
        print_error("Open Transcoder", transcoder.error)
        return False

    # Run transcoder
    if not transcoder.run():
        print_error("Run Transcoder", transcoder.error)
        transcoder.close()
        return False

    transcoder.close()

    print("Encoding completed successfully.")
    return True