[FFmpeg-trac] #4441(avfilter:open): support HDCD

FFmpeg trac at avcodec.org
Sat Nov 28 03:24:01 CET 2015


#4441: support HDCD
-------------------------------------+------------------------------------
             Reporter:  calestyo     |                    Owner:
                 Type:  enhancement  |                   Status:  open
             Priority:  wish         |                Component:  avfilter
              Version:  git-master   |               Resolution:
             Keywords:  hdcd         |               Blocked By:
             Blocking:               |  Reproduced by developer:  1
Analyzed by developer:  0            |
-------------------------------------+------------------------------------

Comment (by cyclonus):

 Jim Lesurf has written some information about HDCP on his homepage:
 http://www.audiomisc.co.uk/HFN/HDCD/Enigma.html

 He has also written misc. audio software:
 http://www.audiomisc.co.uk/software/index.html

 Here he provides the source code for a HDCP decoder:
 http://www.audiomisc.co.uk/software/WAV_HDCDexpander.tgz

 I've successfully compiled PlainVersion.c after some minor 64-bit fixes
 i.e. I had to replace "long" with "uint32_t" in the three structs
 (wav_header, wav_format, wav_data) for obvious reasons.
 I compiled it as follows:

 cc -W -Wall -Wformat=2 -O2 -lm -o hdcd PlainVersion.c

 The resulting executable takes the input file as first and output file as
 second argument.
 Next, I've ripped the only HDCD I own with cdparanoia and converted all
 WAV files with
 the hdcd tool. Apparently it recognized HDCP information in all tracks.

 It seems because the output is a "legacy WAVE" file, mplayer didn't want
 to play them as 24-bit files. After converting them to FLAC "ignoring
 WARNING: legacy WAVE file has format type 1 but bits-per-sample=24", they
 are played as 24-bit files without downsampling to 16-bit.

 The HDCD-decoded files sound different but, of course, I have no way to
 tell whether that's what they're supposed to sound like.

 Further, I tried the same with a normal audio CD. No HDCP information was
 detected.

 Last, I've also downloaded the sample files HDCD32.flac and HDCD16.flac
 and converted them both to WAV. The tool correctly detects HDCD
 information in HDCD16.wav. The output is identical to HDCD32.wav - except
 for header.cksize (3 bytes in the header).

--
Ticket URL: <https://trac.ffmpeg.org/ticket/4441#comment:13>
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