H261 to AMR

Convert H261 to AMR, H261 to AMR Converter

AMR MP3 Converter
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Total Audio MP3 Converter

Convert H261 to AMR


Total Audio MP3 Converter converts H261 files to AMR format. The software is an all in one audio converter that supports more than 90 audio and video files as input, and converts to popular formats such as MP3, WAV, AAC, M4A, OGG, WMA, and AMR.

Total Audio MP3 Converter also supports batch conversion, and is full compatible with Vista and Windows 7.

  1. Free Download Total Audio MP3 Converter here and then install the software by instructions
  2. Launch Total Audio MP3 Converter
  3. Choose H261 Files

  4. Click "Add Files"
    Click "Add Files" to choose H261 files and then add them to conversion list.

    Choose one or more H261 files
    Choose one or more H261 files you want to convert and then click Open.

  5. Choose "to AMR"

  6. Convert to AMR

  7. Convert H261 to AMR

  8. Click Convert
    Click button "Convert" to convert H261 files to AMR format.

    Converting H261 to AMR
    The software is converting H261 files to AMR format.

  9. Play and Browse AMR File

  10. Play and Browse AMR File
    When conversion completes, you could right-click converted AMR file and choose "Play Destination" to play the outputted AMR file; or choose "Browse Destination Folder" to open Windows Explorer to browse the AMR file.
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What is H261?
H.261 is a 1990 ITU-T video coding standard, ratified in November 1988. Originally designed for transmission over ISDN lines on which data rates are multiples of 64 kbit/s. It is one member of the H.26x family of video coding standards in the domain of the ITU-T Video Coding Experts Group (VCEG). The coding algorithm was designed to be able to operate at video bit rates between 40 kbit/s and 2 Mbit/s. The standard supports two video frame sizes: CIF (352x288 luma with 176x144 chroma) and QCIF (176x144 with 88x72 chroma) using a 4:2:0 sampling scheme. It also has a backward-compatible trick for sending still picture graphics with 704x576 luma resolution and 352x288 chroma resolution (which was added in a later revision in 1993).

The H.261 standard actually only specifies how to decode the video. Encoder designers were left free to design their own encoding algorithms, as long as their output was constrained properly to allow it to be decoded by any decoder made according to the standard. Encoders are also left free to perform any pre-processing they want to their input video, and decoders are allowed to perform any post-processing they want to their decoded video prior to display. One effective post-processing technique that became a key element of the best H.261-based systems is called deblocking filtering. This reduces the appearance of block-shaped artifacts caused by the block-based motion compensation and spatial transform parts of the design. Indeed, blocking artifacts are probably a familiar phenomenon to almost everyone who has watched digital video. Deblocking filtering has since become an integral part of the most recent standard, H.264 (although even when using H.264, additional post-processing is still allowed and can enhance visual quality if performed well).

What is AMR?
Adaptive Multi-Rate (AMR) is an audio data compression scheme optimized for speech coding. AMR was adopted as the standard speech codec by 3GPP in October 1998 and is now widely used in GSM and UMTS. It uses link adaptation to select from one of eight different bit rates based on link conditions. AMR is also a file format for storing spoken audio using the AMR codec. Many modern mobile telephone handsets will allow you to store short recordings in the AMR format. There also exists another storage format for AMR that is suitable for applications with more advanced demands on the storage format, like random access or synchronization with video. This format is the 3GPP-specified 3GP container format based on ISO base media file format.

Key Features:

  • Sampling frequency 8 kHz/13-bit (160 samples for 20 ms frames), filtered to 200-3400 Hz.
  • The AMR codec uses eight source codecs with bit-rates of 12.2, 10.2, 7.95, 7.40, 6.70, 5.90, 5.15 and 4.75 kbit/s.
  • Generates frame length of 95, 103, 118, 134, 148, 159, 204, or 244 bits for bit rates 4.75, 5.15, 5.90, 6.70, 7.40, 7.95, 10.2, or 12.2 kbit/s, respectively
  • AMR utilizes Discontinuous Transmission (DTX), with Voice Activity Detection (VAD) and Comfort Noise Generation (CNG) to reduce bandwidth usage during silence periods
  • Algorithmic delay is 20 ms per frame. For bit-rates of 12.2, there is no 'algorithm' look-ahead delay. For other rates, look-ahead delay is 5 ms. Note that there is 5 ms 'dummy' look-ahead delay, to allow seamless frame-wise mode switching with the rest of rates.
  • AMR is a hybrid speech coder which uses Algebraic Code Excited Linear Prediction (ACELP)
  • The complexity of the algorithm is rated at 5, using a relative scale where G.711 is 1 and G.729a is 15.
  • PSQM testing under ideal conditions yields Mean Opinion Scores of 4.14 for AMR (12.2 kbit/s), compared to 4.45 for G.711 (u-law)
  • PSQM testing under network stress yields Mean Opinion Scores of 3.79 for AMR (12.2 kbit/s), compared to 4.13 for G.711 (u-law)

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