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Ultimedia Services Version 2 for AIX: Programmer's Guide and Reference

Programming with the Movie Capture Object

To learn more about programming with the Movie Capture object, see:

For introductory information, see Programming with Movie Capture and VideoIO Objects.

UMSCapture Methods

UMSCapture includes capture controls, media record controls, video device controls, audio device controls, media attribute controls for video, media attribute controls for audio, and media monitoring controls.

Capture Controls

Capture controls include:

open_video Opens the video device.
open_audio Opens the audio device.
close_video Closes the video device.
close_audio Closes the audio device.
save Saves a file.
reset_tempfile Reuses the fast format file (temporary file).
cancel_save Stops a save.
get_state Returns current state.

Media Record Controls

Media record controls include:

record Records video/audio data into a temporary file defined in UMS_config configuration file.
pause Pauses record.
resume Resumes record.
stop Stops record.

Video Device Controls

Video device controls include:

set_video_input_connector Enables video input for recording.
set_analog_video_format Sets NTSC or PAL as the input video format.
set_analog_video_monitor Enables or disables monitoring video on video monitor.

Audio Device Controls

Audio device controls include:

enable_audio_connector Enables audio input and output for recording and monitoring.
set_volume Sets volume.
set_balance Sets balance.
set_audio_monitor Enables or disables monitoring of audio.

Media Attribute Controls for Video

Media attribute controls for video include:

set_input_image_size Sets input video size.
set_capture_rate Sets capture speed (frames per second).
set_quality_factor Sets captured image quality.
set_q_table Sets quantization tables.
set_Huffman_table Sets Huffman tables.
set_subimage_size Sets to capture part of input image.

Media Attribute Controls for Audio

Media attribute controls for audio include:

set_audio_capture Sets to capture audio data during the record.
set_audio_format_type Sets audio data format.
set_audio_sample_rate Sets the sample rate (samples per second).
set_audio_bits_per_sample Sets number of bits per sample.
set_number_channels Sets mono or stereo.
set_audio_byte_order Sets byte order to either most significant byte first or least significant byte first.
set_audio_number_format Sets byte format to unsigned, signed, or twos complement.

Media Monitoring Controls

Media monitoring controls include:

set_window Sets an AIXwindows window display ID and window ID for monitoring.
set_window_monitor Enables monitoring on an AIXwindows window.
set_monitor_image_format Sets image format for window monitoring (RGB8 or RGB24).
get_colormap_id Gets color map ID for monitoring the window.
set_colormap Sets color map.
set_colormap_index Sets the start entry of the color map.
set_colormap_size Sets the size of the color map.
release_window Releases the window back to the application.
get_event Gets the next event.
event_pending Determines if the event is available.
get_event_handle Returns the file descriptor for event communication.
get_number_of_missing_frames Returns how many frames missed and how many frames captured in the most current record.

Recording a Movie File

The capture object uses the record method to capture video/audio data to a temporary file and the save method to convert it to an AVI file. Recording is paused by the pause method and resumed by the resume method. Note that during recording, audio or video media attributes must not be alternated.

To record a movie, do the following:

  1. Initialize the SOM environment.
  2. Create an instance of a UMSCapture object.
  3. Using an alias, open (using open_video) a video device (defined in the configuration file).
  4. Using an alias, use open_audio to open an audio device (defined in the configuration file).
  5. Specify the source of the recorded data using set_video_input_connector and enable_audio_connector.
  6. Issue the record method.
  7. To stop recording, use the stop method.
  8. Save the file using the save method.


The movie capture object uses different types of connectors to indicate the input video/audio source for recorded data. The set_video_input_connector method allows choices of either INPUT_COMPOSITE or INPUT_SVIDEO. The enable_audio_connector method input connector allows choices of LINE_IN, HIGH_GAIN_MIC, or LOW_GAIN_MIC. The INPUT_COMPOSITE connector is used to provide a composite video baseband signal for recording. INPUT_SVIDEO connector is used for S-Video devices. The LINE IN connector typically is used to provide line level input. LOW_GAIN_MIC is used for microphones not providing their own amplification, while HIGH_GAIN_MIC is used for microphones that provide amplification.

For introductory information, see Programming with Movie Capture and VideoIO Objects.

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