As a centralized media-processing engine for any-to-any video transcoding, the Cisco® MXE 3000 Media Experience Engine efficiently processes video work in a variety of ways. One of its main differentiators from its competition is its ability to decode a video file once and then simultaneously process it in the multiple different output formats, otherwise known as preprocessing. This technical brief covers the different types of preprocessing settings and how they allow for efficient encoding.
The Cisco MXE 3000 integrates the five steps of the media production and distribution cycle through its user interface:
1. Choose source: Jobs are submitted using the File Job tab.
2. Preprocess: Preprocessing is controlled by the Preprocessor tab. Jobs may include preprocessor settings that adjust many video and audio settings. Only one Preprocessor tab is needed for each job or job profile.
3. Encode: Encoding is controlled by Encoder tabs. Each type of Encoder tab corresponds to a specific type of encoding, including Flash 8, H.264, MP3, MPEG, QuickTime, Real, WAV, and Windows Media. You can add one or more encoders in any combination to a job or job profile.
4. Distribute: Distribution of processed media files is controlled by Distribution tabs, which allow you to specify which files are stored locally, how files are named, and where files are delivered.
5. Submit: When all Job, Preprocessor, Encoder, and Distribution tabs have been added and settings applied to each tab, Submit the job and manage the job status.
While video jobs are being processed, during preprocessing and encoding, the Cisco MXE 3000 does the following (Figure 1):
A. It decodes a file-based video to an uncompressed AVI file.
B. It writes the uncompressed AVI file to a disk (default behavior) or memory.
C. Each encoder reads the AVI file as a source and outputs the appropriate format.
Figure 1. Video Pipeline
Three types of decoding and encoding processes for the Cisco MXE 3000 can create processing efficiencies:
• Normal
• Immediate
• Fast start
Normal Encoding
The uncompressed AVI file is written to a disk (the default behavior) and then all encoding formats are created and processed in parallel by reading the uncompressed file contents off the disk.
Immediate Encoding
Typically, the Cisco MXE 3000 generates an intermediate uncompressed AVI file as the output of the preprocessing step. If immediate encoding is enabled, the Cisco MXE 3000 does not use an intermediate file, but uses a memory-based interface between the preprocessor and the encoders. This interface is extremely useful for longer input clips or formats with high data volumes, such as MPEG, where the disk space requirements for intermediate files could become prohibitive.
The Cisco MXE 3000 supports immediate encoding for the following encoders: Flash 8, H.264, MPEG, MXF, Real, and Windows Media.
Fast-Start Encoding
Fast-start encoding reduces the total time required to process a job by starting the encoding process as soon as enough of the image has been preprocessed, rather than waiting for the preprocessing to be completed. Customers typically use this feature when submitting large jobs.
Because fast-start encoding uses available computer processing cycles, the Cisco MXE 3000 uses fast-start encoding only under the following circumstances:
• If at most one other clip is currently encoding
• If bumpers and trailers are not specified in the preprocessing profile
Table 1 shows the input and output formats that immediate and fast-start decoding and encoding support.
Table 1. Format Support for Immediate, Fast Start, and Normal Decoding and Encoding
Format
Immediate
Fast Start
Normal
Avid JFIF*
√
√
√
Avid DV*
√
√
√
Avid DNxHD*
√
√
√
DV
√
√
√
Flash 7
√
√
Flash 8
√
√
√
Grass Valley
√
√
√
H.264
√
√
√
Leitch
√
√
√
MP3
√
√
MPEG1
√
√
√
MPEG2
√
√
√
MXF DV*
√
√
√
MXF DVCpro*
√
√
√
MXF IMX*
√
√
√
MXF MPEG2*
√
√
√
Omneon*
√
√
√
Pinnacle*
√
√
√
QuickTime
√
√
Real Media
√
√
√
VOD MP2
√
√
WAV audio
√
√
Windows Media
√
√
√
Indexing
√
Thumbnails
√
√
√
Caption extract
√
√
√
*The Cisco MXE 3000 supports this format as an input only.
Questions
Q. What input formats support immediate-mode preprocessing?
A. Immediate mode depends on output format; input does not affect it.
Q. What output formats support immediate-mode encoding?
A. Refer to Table 1.
Q. What input formats support fast start-mode preprocessing?
A. Immediate mode depends on output format; input does not affect it.
Q. What output formats support fast start-mode encoding?
A. Refer to Table 1.
In summary, the way in which media processing devices process content greatly impacts the efficiency involved in delivering content, quickly and accurately. The MXE 3000 uses unique preprocessing techniques described above to ensure that content is processed and delivered in the most efficient manner possible. This improves the turnaround time associated with processing jobs and also frees up cycles on the processing hardware that could be expended for other jobs.
