[FFmpeg-devel] [PATCH] af_hdcd.c: only hdcd_update_info() when something changes, add error detection

[Michael Niedermayer]

On Mon, Jul 11, 2016 at 05:33:03PM -0500, Burt P. wrote:

> Only call hdcd_update_info() when the control code changes
> instead of every frame, so the counters are more meaningful.
> 

> Also, adds some basic error detection. After scanning through
> about 30 HDCD-encoded CD's I've found errors where a code
> is signaled, but then fails to match one of the patterns, so
> it is ignored. Often, it is very close to a code, differing
> by only one bit. I don't know enough to say whether it is
> using some unknown feature of HDCD that this filter doesn't
> know about, or if there was just an error in the encoding.
> I've added some comments so that it should be easier for
> others to examine.

are these 2 seperate changes ?
if so they should be in seperate patches/commits


> 
> An example with many errors is Līve - Secret Samadhi, if
> anyone wants to look into it.
> 
> Patch is attached.
> Any comments would be appreciated.

>  af_hdcd.c |  122 ++++++++++++++++++++++++++++++++++++++++----------------------
>  1 file changed, 79 insertions(+), 43 deletions(-)
> e787817ad5f053390d648e6bba66f9a2fd5d0e95  0001-af_hdcd.c-only-hdcd_update_info-when-something-chang.patch
> From 63a2736dd8444fe64d8c5bc885d61979bfe93f6b Mon Sep 17 00:00:00 2001
> From: Burt P <pburt0 at gmail.com>
> Date: Mon, 11 Jul 2016 17:08:20 -0500
> Subject: [PATCH] af_hdcd.c: only hdcd_update_info() when something changes,
>  add error detection
> MIME-Version: 1.0
> Content-Type: text/plain; charset=UTF-8
> Content-Transfer-Encoding: 8bit
> 
> * hdcd_update_info() when control code changes; counts are more meaningful
> * some encoding errors can be detected
> * fewer false positives by ignoring code_counterC in HDCD detection
> * integrate() renamed hdcd_integrate() to be consistent with the other function names
> * some code comments
> 
> Try Līve - Secret Samadhi or John Mellencamp - Mr. Happy Go Lucky for error detection.

[...]

> +                av_log(0, AV_LOG_VERBOSE,
> +                    "hdcd error: Control A almost: 0x%08x\n", bits);

[...]

> +            av_log(0, AV_LOG_VERBOSE,
> +                "hdcd error: Unmatched code: 0x%08x\n", bits);

av_log() should have a non null context so that the messages can more
easily be associated with their source

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I do not agree with what you have to say, but I'll defend to the death your
right to say it. -- Voltaire
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