[mythtv-users] BBC HD recorded show length wrong in mythfrontend

belcampo belcampo at zonnet.nl
Sun Sep 20 13:04:26 UTC 2009


David Knight wrote:
> On Sun, September 20, 2009 12:42 am, belcampo wrote:
>> Here
>> http://compression.ru/video/codec_comparison/mpeg-4_avc_h264_2005_en.html
>> one can read that some encoders are much more efficient than others for
>> the same quality.
>>> I also used to be able to watch the recordings on my Windows PC through
>>> Mythweb asx stream but that doesn't work anymore (guessing this is the
>>> encoder change) Windows Media Player reports that the codec is unknown.
>> The installed software is to blame. Hardware encoders working according
>>   to the h264 specs work without a problem.
> 
>> A month ago I wrote this on the ffmpeg-user list
>>
>> BBCHD fps mis-interpretation
>>
>> It seems BBCHD streams from DVB-S have changed, it always was MBAFF
>> interlaced, now it is interpreted as 50fps
>> Stream #0.0[0x157c]: Video: h264, yuv420p, 1440x1080 [PAR 4:3 DAR 16:9],
>> 50 tbr, 90k tbn, 50 tbc
>>
>> Although mediainfo for the same file says:
>>
>> Frame rate                       : 25.000
>> Frame rate                       : 25.000 fps
>> Frame count                      : 97582
>> Resolution                       : 24
>> Resolution                       : 24 bits
>> Colorimetry                      : 4:2:0
>> Scan type                        : Interlaced
>> Scan type                        : Interlaced
>> Scan order                       : TFF
>> Scan order                       : Top Field First
>> Interlacement                    : TFF
>>
>>
> 
> Hi Belcampo,
> 
>    I understand that some encoders are more efficient than others. But the
> detoriation in quality is noticeable with BBC HD - hence the BBC's
> response to a large number of complainents.
I doubt that what you seem to see has to something to do with it. I 
would be very interested to know what people, who have complaints, use 
to watch.

Recorded something a few hours ago and the bitrate relevant part is:
Bit rate                         : 13.1 Mbps
Width                            : 1440
Height                           : 1080
Bits/(Pixel*Frame)               : 0.337
> 
>    You also mentioned that hardware encoders don't have problems yet the
> BBC say there is a problem which they have raised with their encoder
> suppliers... -
The BBC mentions:
Following the introduction of the new encoders, there were some issues 
around the handling of some pictures - primarily mixes and fades - which 
we acknowledged through the BBC HD blog on picture quality almost 
immediately.

In my opinion the part "some issues and some pictures" says it.
> http://whathifi.com/News/BBC-admits-to-problems-with-new-HD-encoders/
> 
>    Has there been any feedback on the FFMPEG list yet?
No, nobody seems to care.
I 'solved' it by using an older SVN-r17923 compiled with x264 version 
65. Current SVN with x264 75 is horrible.
BTW I use NMT PopCornhour to watch my mythtv-recordings, never use 
mythtv for that, because of the lower quality.
> 
> Dave K.
> 
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