LEADTOOLS Filters Help
| LEADTOOLS Filters Help > Filters, Codecs and Interfaces > Audio Codecs > AAC Transcoder > LEAD AAC Transcoder |
Transcoder: A file format convertion process that is executed by data re-packetizing. Transcoding avoids decoding and re-compression thus providing speed gains over decoding-encoding methods used in traditional filters. Additionally, LEADTOOLS transcoders preserve data quality by avoiding re-compression of already compressed data.
A multimedia framework and API produced by Microsoft for software developers to perform various operations with media files. Most Windows video-related applications on Windows, such as Microsoft's Windows Media Player, use DirectShow to manage multimedia content.
The LEAD AAC Transcoder is a DirectShow ® filter. It is used to transcode AAC audio stream in mpeg2 format to ACC in ISO (mpeg4) format or vice versa. This filter changes AAC packets format without performing re-compression of the audio stream or the data packets. Converting with this filter is fast, while the quality of the original stream is preserved. To convert without re-compression, an AAC stream inside a MPEG2 transport file to ISO format, or vice versa, LEAD AAC Transcoder filter should be inserted between mpeg2 demux and ISO multiplexer. LEAD Multimedia toolkit automatically inserts the filter in this manner.
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Filter Interfaces |
N/A |
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Interface ID |
N/A |
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Input Media Types |
Type: MEDIASUBTYPE_mp4a |
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Output Media Types |
Type: MEDIASUBTYPE_AAC |
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Filter CLSID |
CLSID_LMAACTranscoder |
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Filter category |
CLSID_AudioCompressorCategory |
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Executable |
LTranscoderAAC.dll, DSKernel2.dll |
Win32, x64
To illustrate the advantage of using transcoders, two setups are provided below for comparison. Observe (Figure 1) how the transcoders are positioned between LEAD MPEG Transport Demultiplexer and LEAD ISO Multiplexer. Now observe the next image (Figure 2) and how in between the same LEAD MPEG2 Transport Demultiplexer and LEAD ISO Multiplexer there is a need to use encoders and decoders. As a result of using decoding-encoding filters, the processing of data is slower than the speeds attained with data re-packetizing - a key feature of transcoders.
Figure 1. Re-packetizing of data using transcoders.
Figure 2. Decoding and encoding of data using filters.
