BBC Radio Broadcast Standards- Freeview & Freesat

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BBC Radio Broadcast Standards- Freeview & Freesat

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lavagiant

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This is a real 'geeky' question!

I contacted BBC to find out the broadcast standard for BBC Radio 2 on both Freesat and Freeview. The email back from the BBC Reception Advise was that they are both broadcast 128kbs using MPEG2 type format.

I have both HDR-FOXSAT and HDR-FOX-T2 and looking at the TS file from the same recording on VLC, the files show as MP3 @ 128kbs, does the Humax boxes then convert the files?

Also, the FOXSAT box file size on a 2 hour recording is 190 MB and the Fox-T2 file size is around 730MB for the same recording. Can someone comment on why the huge difference?

Also - when using the Iplayer on the Fox-T2 and then saving the broadcast using custom firmware, the file is 128K MP4, is there any conversion from MP2 to MP4 or is the file genuinely MP4 on download ??

I've spent ages trying to find out this info but have failed, I wondered if someone out there can confirm my points,
I'm trying to listen to some of my favourite programs in the best possible way.

Thank you.

LavaGiant

| Fri 11 Oct 2013 13:51:15 #1 |
grahamlthompson

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Hi welcome to the forum.

I have set Radio 4 (Channel 704) to record Gardeners Question Time 15:00-15:45 today on Foxsat-hdr and HDR FOX T2. Will post resulting file details.

I don't think mpeg2 is correct. I guess the audio will be the same as SD TV ie mpeg1 layer 2 (MP2) format. mpeg2 is a video compression format as used in DVD-Video and SD digital TV.

| Fri 11 Oct 2013 14:06:51 #2 |
lavagiant

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I think I may be getting confused (which is getting too frequent now).

This is the BBC response:

I forwarded your correspondence to our investigation team who inform me that Radio 2 uses Mpeg 1 layer 2 compression for both Freesat and Freeview at a bit rate of 192kbps.

I just assumed that this was MPEG2.

I listen to most content on a portable media player and can have MP2/MP3 or even MP4. I can hear the difference between MP2 and MP3 at 128kbps so was trying to get the best I can. MP4 is awkward on my media player so I would convert MP4 to MP3.
Anyway, I take it that Mpeg1 layer 2 is mot MPEG2 ?

Thanks Graham in advance.

| Fri 11 Oct 2013 14:20:04 #3 |
Martin Liddle

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lavagiant - 54 minutes ago »
Also, the FOXSAT box file size on a 2 hour recording is 190 MB and the Fox-T2 file size is around 730MB for the same recording. Can someone comment on why the huge difference?

This is a known issue; for some reason the Humax records vast amounts of additional meta data. The custom firmware for the HDR-FOX T2 includes a utility to remove the additional data called (I think) stripts.

| Fri 11 Oct 2013 14:48:35 #4 |
af123

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I think Mpeg 1 layer 2 is usually referred to as MP2

(certainly MP3 is MPEG 1 or MPEG2 layer 3)

The huge size difference between the recordings on the different platforms is because the Fox-T2 saves parts of the broadcast stream in the recording. In particular it stores all EPG data which is being transmitted on the multiplex which can account for a massive overhead, particularly on radio recordings. This is the data that the custom firmware shrink process removes to reduce the storage requirement of recordings.

| Fri 11 Oct 2013 14:48:37 #5 |
grahamlthompson

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lavagiant - 49 minutes ago »

Anyway, I take it that Mpeg1 layer 2 is mot MPEG2 ?
Thanks Graham in advance.

Correct

See the first line in this wiki

http://en.wikipedia.org/wiki/MPEG-2

| Fri 11 Oct 2013 15:10:58 #6 |
grahamlthompson

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Details (as expected Mpeg1 Layer 2 audio in transport stream container)

I have stripts installed, will post what happens to the filesize.

General ID : 4165 (0x1045) Complete name : E:\Radio\FreeviewRadio.ts Format : BDAV Format/Info : Blu-ray Video File size : 282 MiB Duration : 44mn 55s Overall bit rate : 878 Kbps
Audio ID : 1302 (0x516) Menu ID : 6912 (0x1B00) Format : MPEG Audio Format version : Version 1 Format profile : Layer 2 Mode : Joint stereo Mode extension : Intensity Stereo + MS Stereo Codec ID : 3 Duration : 44mn 55s Bit rate mode : Constant Bit rate : 192 Kbps Channel(s) : 2 channels Sampling rate : 48.0 KHz Compression mode : Lossy Stream size : 61.7 MiB (22%) Language : English Menu ID : 1300 (0x514) Menu ID : 6912 (0x1B00) Duration : 44mn 55s List : 1302 (0x516) (MPEG Audio, English) Language : English Service name : BBC Radio 4 Service type : digital radio UTC 2013-10-11 00:00:00 : en:As BBC World Service / en:BBC Radio 4 joins the BBC World Service. / news/current affairs / / 04:20:00 / UTC 2013-10-13 00:00:00 : en:As BBC World Service / en:BBC Radio 4 joins the BBC World Service. BBC Radio 4 resumes at 5.20am. / news/current affairs / / 04:20:00 / UTC 2013-10-14 00:00:00 : en:As BBC World Service / en:BBC Radio 4 joins the BBC World Service. / news/current affairs / / 04:20:00 / UTC 2013-10-17 00:00:00 : en:As BBC World Service / en:BBC Radio 4 joins the BBC World Service. / news/current affairs / / 04:20:00 / General ID : 2046 (0x7FE) Complete name : E:\Radio\FreesatRadio.ts Format : BDAV Format/Info : Blu-ray Video File size : 69.4 MiB Duration : 44mn 58s Overall bit rate : 216 Kbps Audio ID : 6002 (0x1772) Menu ID : 10381 (0x288D) Format : MPEG Audio Format version : Version 1 Format profile : Layer 2 Mode : Joint stereo Mode extension : Intensity Stereo + MS Stereo Codec ID : 3 Duration : 44mn 58s Bit rate mode : Constant Bit rate : 192 Kbps Channel(s) : 2 channels Sampling rate : 48.0 KHz Compression mode : Lossy Stream size : 61.8 MiB (89%) Language : English Menu ID : 275 (0x113) Menu ID : 10381 (0x288D) Duration : 44mn 58s List : 6002 (0x1772) (MPEG Audio, English) Language : English

| Fri 11 Oct 2013 16:23:02 #7 |
af123

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grahamlthompson - 1 hour ago »

lavagiant - 49 minutes ago »
Anyway, I take it that Mpeg1 layer 2 is mot MPEG2 ?
Thanks Graham in advance.

Correct
See the first line in this wiki
http://en.wikipedia.org/wiki/MPEG-2

See also http://en.wikipedia.org/wiki/MPEG-1_Audio_Layer_II
MPEG 1 Audio Layer II is called MP2 (NOT MPEG 2).

| Fri 11 Oct 2013 16:24:13 #8 |
lavagiant

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af123 - 1 hour ago »

grahamlthompson - 1 hour ago »

lavagiant - 49 minutes ago »
Anyway, I take it that Mpeg1 layer 2 is mot MPEG2 ?
Thanks Graham in advance.

Correct
See the first line in this wiki
http://en.wikipedia.org/wiki/MPEG-2

See also http://en.wikipedia.org/wiki/MPEG-1_Audio_Layer_II
MPEG 1 Audio Layer II is called MP2 (NOT MPEG 2).

This is harder to understand than my Cisco Accreditation !

Thank all for this, I'm going to have to look into these files and the containers etc. I set myself a challenge of listening to a WAV file from CD recorded via VLC and then converted to MP3 and MP4 at various bit rates, I could hear a very, very slight difference at 128k and again at 80k the MP4 was still good. At 192K difference is minimal.
I knew that I was never happy with DAB which is MP2 at 128k I believe for R2.
I think thats my confusion and I did read a wiki explanation that confirmed what I had originally thought, so I shouldn't have thought that this was gospel (I don't like wiki stuff unless I can confirm elsewhere).

Probably best just to get a recording of something in my CD collection and compare the broadcast with the CD and see how good it is.
It would be interesting for me if someone could see my original post about the Iplayer stream saved via web interface and confirm its genuinely MP4.
I've used the 'get_iplayer' program via Ubuntu and also delivers content as MP4 if I recall at 192K so I need to do a listening test as I'd like to get the purest source. The 'Get_Iplayer' mimics the Iphone Iplayer App I'm told.

Thank you for being so kind to me so far on my quest.

| Fri 11 Oct 2013 18:12:43 #9 |
grahamlthompson

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If you want to look in detail what a particular audio/video file contains try Medianinfo.

http://mediaarea.net/en/MediaInfo

| Fri 11 Oct 2013 18:46:26 #10 |