[mythtv-users] chirping in recordings with pchdtv hd-3000's and 0.21

Tom Dexter digitalaudiorock at gmail.com
Thu Apr 17 02:47:28 UTC 2008


On Wed, Apr 16, 2008 at 4:57 PM, Tom Dexter <digitalaudiorock at gmail.com> wrote:
>
>  Here's what my patch looks like (I've attached it as well):
>
>  Index: libavcodec/ac3dec.c
>  ===================================================================
>  --- libs/libavcodec/ac3dec.c
>  +++ libs/libavcodec/ac3dec.c
>  @@ -37,6 +37,7 @@
>   #include "bitstream.h"
>   #include "dsputil.h"
>   #include "random.h"
>  +#include "crc.h"
>
>   /**
>   * Table of bin locations for rematrixing bands
>  @@ -1121,6 +1122,12 @@
>          return -1;
>      }
>
>  +    if (av_crc(av_crc8005, 0, buf + 2, buf_size - 2)) {
>  +        av_log(avctx, AV_LOG_ERROR, "CRC error\n");
>  +        *data_size = 0;
>  +        return buf_size;
>  +    }
>  +
>      avctx->sample_rate = ctx->sampling_rate;
>      avctx->bit_rate = ctx->bit_rate;
>

After tonight I can definitely say that this patch is working very
well.  I got a few really significant instances of recording
corruption...funnily enough from cutting a chicken with an electric
carving knife :D...that old thing apparently makes a pretty good OTA
jamming device.

With enough corruption to seriously pixelate the video for several
seconds at a time, I not only experienced no audio noise of any kind,
often the dropped audio (reported in the logs as CRC errors) wasn't
even audible.

Tom


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