About the MPEG-4 Part 2 Encoder Pane

The MPEG-4 Part 2 Encoder pane allows you to select a variety of streaming types and options.

Figure. MPEG-4 Part 2 Encoder pane of the Inspector window.

MPEG-4 Encoder Pane General Settings

The MPEG-4 Part 2 pane contains the following items:

  • File Extension field: Displays the MPEG-4 Part 2 file extension (.mp4) as soon as the MPEG-4 output format is selected from the File Format pop-up menu or the (+) pop-up menu in the Settings tab.
  • Allow Job Segmenting: This checkbox allows you to turn off job segmenting. It is relevant only if you are using Compressor with distributed processing and with multi-pass encoding. Since the MPEG-4 Part 2 format uses single-pass VBR, you can leave this checkbox selected in all cases for added speed gains with distributed processing. For more information, see Job Segmenting and Two-Pass or Multi-Pass Encoding.
  • Video, Audio, and Streaming buttons: These buttons open the Video, Audio, and Streaming panes, described next.
  • Enhanced Podcast (m4a file): Select this checkbox to ensure that podcasting annotations and metadata are written to the output media file. This is available for audio files only. To make this option available, deselect the Video Enabled checkbox at the top of the Video pane.
  • Fit marker images within: Use this to specify the width and height of the podcast marker images when creating an audio podcast. You can also click the Automatic button to have Compressor enter the values. This option is only available when the Video Enabled checkbox at the top of the Video pane is deselected. See Stage 5: Creating and Configuring Markers for the Output Media File for more information.

Video Pane

The Video pane allows you to make settings for the quality (ISMA profile), frames per second (fps) rate, key frame interval, and bit rate of your MPEG-4 Part 2 output file.

Figure. Video pane.

The pane contains the following controls.

  • Video Enabled checkbox: Make sure that this checkbox is selected if you want the MPEG-4 Part 2 output format video settings to be applied.
  • Frame Rate (fps) pop-up menu and field: Choose or enter a number to set the overall frame rate of your output media file, or click the Automatic button to have Compressor choose the frame rate.
  • Key Frame Interval field: Enter a value to designate how often (number of frames) you want key frames created in your output media file, or click the Automatic button to have Compressor choose the key frame interval rate (the displayed value is 0 with Automatic on; the actual value is determined during the encoding process).
  • Multi-pass: Select this for higher-quality results but at the expense of longer encoding times. This is only available when you choose an H.264 option from the “Video compression” pop-up menu.
  • Bit Rate slider and field: Move the slider to set the overall video bit rate for your output media file, or enter a specific number in the accompanying field.

Audio Pane

You use the Audio pane to set the audio track quality, sample rate, quality, and bit rate of the MPEG-4 output file.

Figure. Audio pane.

Use the following buttons and slider to make more detailed adjustments.

  • Audio Enabled checkbox: Make sure that this checkbox is selected if you want the MPEG-4 Part 2 output format audio settings to be applied.
  • Channels buttons: Choose the audio channel for your output media file to be either mono or stereo.
    • Mono: Choose this button for mono output.
    • Stereo: Choose this button for stereo output.
  • Bit Rate slider and field: Move the slider to set the overall audio bit rate for your output media file between the range of 16 kbps (2 KB/sec.) and 320 kbps (40 KB/sec.), or enter a specific number in the accompanying field.

Streaming Pane

You use the Streaming pane to set hints for your output file, as well as set the maximum packet size and packet duration limits of the MPEG-4 Part 2 output file. You can also set your output media file to work with an older version of QuickTime Streaming Server (version 4.1 or earlier).

Figure. Streaming pane.

The Streaming pane contains the following controls.

  • Streaming hints enabled checkbox: Make sure that this checkbox is selected if you want the MPEG-4 Part 2 output format streaming settings to be applied.
  • QuickTime Streaming Server Compatibility (pre 4.1) checkbox: Select this checkbox if you want your output media file to work with an older QuickTime Streaming Server (version 4.1 or earlier). You don’t need to select this checkbox if you are using a newer version of QuickTime, because any streaming compatibility issues are automatically resolved.
  • Packet Maximum Size field: Enter a number to specify the largest file size allowable (in bytes) for a streaming packet in your output media file. The packet size you choose should be no larger than the largest packet used on any network between the streaming server and the viewer.
  • Packet Maximum Duration field: Enter a number to specify the longest duration allowable (in milliseconds) for a streaming packet in your output media file. The duration affects MPEG-4 Part 2 audio only. It limits the maximum amount of audio (in milliseconds) in any packet, which limits the audio dropout created by the loss of a packet.