Opened 9 years ago
Last modified 9 years ago
#4142 new enhancement
Fourth Generation Vocoder
| Reported by: | Carl Eugen Hoyos | Owned by: | |
|---|---|---|---|
| Priority: | wish | Component: | avcodec |
| Version: | git-master | Keywords: | qcp |
| Cc: | Blocked By: | ||
| Blocking: | Reproduced by developer: | no | |
| Analyzed by developer: | no |
Description (last modified by )
A user uploaded a qcp file with an unknown GUID {3CFD29CA-F653-4EF5-90E9-F4236D599B61} containing Fourth Generation Vocoder (4GV).
$ ffmpeg -i 0812001631.qcp ffmpeg version N-68112-ge4788e9 Copyright (c) 2000-2014 the FFmpeg developers built on Nov 30 2014 00:45:08 with gcc 4.7 (SUSE Linux) configuration: --enable-gpl libavutil 54. 15.100 / 54. 15.100 libavcodec 56. 13.100 / 56. 13.100 libavformat 56. 15.101 / 56. 15.101 libavdevice 56. 3.100 / 56. 3.100 libavfilter 5. 2.103 / 5. 2.103 libswscale 3. 1.101 / 3. 1.101 libswresample 1. 1.100 / 1. 1.100 libpostproc 53. 3.100 / 53. 3.100 [qcp @ 0x238fba0] Unknown codec GUID. 0812001631.qcp: Invalid data found when processing input
Attachments (1)
Change History (9)
by , 9 years ago
| Attachment: | 0812001631.qcp added |
|---|
comment:1 by , 9 years ago
| Description: | modified (diff) |
|---|
comment:2 by , 9 years ago
comment:3 by , 9 years ago
AFAIK there is no single document that mentions this guid, why you think it have anything in common with 4GV?
comment:7 by , 9 years ago
I managed to decode this file (first you need to add 16bit frame type to each packet and convert bitstream from bigendian to little endian) with reference decoder EVRC-B.
Reference decoder EVRC-C with its executable with name fourgv did not correctly decoded file. So this file probably is not EVRC-WB.
I failed to find GUID as used in qcp on internet and fourcc (if) used in 3gpp2 files.
comment:8 by , 9 years ago
According to this site http://droid-dev.mobi/wiki/Qualcomm_QSC6085 4GV is just another name for EVRC-B.
From Wikipedia:
Currently, the 4GV suite offers EVRC-B and EVRC-WB.
Enhanced Variable Rate Codec B (EVRC-B) is a speech codec used by CDMA networks. EVRC-B is an enhancement to EVRC and compresses each 20 milliseconds of 8000 Hz, 16-bit sampled speech input into output frames of one of the four different sizes: Rate 1 - 171 bits, Rate 1/2 - 80 bits, Rate 1/4 - 40 bits, Rate 1/8 - 16 bits.
In addition, there are two zero bit codec frame types: null frames and erasure frames, similar to EVRC. One significant enhancement in EVRC-B is the use of 1/4 rate frames that were not used in EVRC. This provides lower average data rates (ADRs) compared to EVRC, for a given voice quality. The new 4GV Codecs used in CDMA2000 are based on EVRC-B.