MPEG-4 or MPEG-2?

[KeithAbb0tt]

I have a couple of HDHomeRun Primes connected to SageTV via OpenDCT. I looked at the Channel Lineup displayed in the Prime's webgui this morning, it is showing an AVC icon for every channel but two, which are channels that I would not watch anyhow. According to SilidonDust, "AVC means it is distributed by the provider as h.264 rather than the more common MPEG2".

But here's the weird part. When I look at the recording detail in SageTV for shows that have been recorded from my Prime, they show "MPEG2-TS[H.264 16:9 720p@60fps, ...". I was under the impression that H.264 implies MPEG4. Can anyone provide any insight as to what might be going on here? Do I have a setting within either SageTV or OpenDCT that is converting the recordings from MPEG4 to MPEG2?

[KeithAbb0tt]

Did some additional checking, all of my prime tuners in OpenDCT are set to opendct.consumer.FFmpegTransSageTVConsumerImpl (which I believe is the default). I'm wondering if I need to change them to either opendct.consumer.RawSageTVConsumerImpl or opendct.consumer.MediaServerConsumerImpl

Anyone have any insight or recommendations? Anybody getting MPEG4 out of your Prime?

[trk2]

I think this just means the encoding is h.264 (MPEG4) inside an MPEG2-TS container.

[jwittkoski]

tl'dr: Your recordings are MPEG4 recordings.

My HDHomeRun Prime and InfinitiTV recordings look similar.

The names are confusing - they mean multiple things because there are different parts to each standard and in most cases people use just the "abbreviated" name.

MPEG2 could mean:
MPEG-2 the container format (MPEG-2 Part 1, usually referred to as MPEG2-TS or MPEG2-PS)
MPEG-2 the video compression codec (MPEG-2 Part 2).

MPEG4 could mean:
MPEG-4 the container (MPEG-4 Part 14, the "mp4" file)
MPEG-4 the video compression codec (MPEG-4 Part 10 (H.264/AVC))

Both standards have other parts that are for other purposes (audio, for example).

Most container formats are codec agnostic so they can hold multiple types of codecs. An MPEG-2 container can hold an MPEG-4 codec (common) or an MPEG-4 container could hold an MPEG-2 codec (technically possible but rarely actually used).

What we both get from HDHomeRun Prime and InfinitiTV tuners in this case is an MPEG2-TS container with MPEG-4 Part 10 (H.264) encoded video stream.

I have older recordings (before most of my provider's channels went to H.264/AVC codecs) that are listed as MPEG2-TS with MPEG2 video encoding. The SiliconDust statement you quoted is referring to providers using MPEG2 video codecs in the past instead of H.264/AVC which is more common now. It is not referring to the container format, which for most people is still MPEG2-TS.

[KeithAbb0tt]

Thank you both for the responses, I am kicking myself for not running MediaInfo on a few of the recordings before I created this post. Although I probably would have still been a bit confused, but your responses cleared everything up for me.

That said, I ran MediaInfo on quite a few of the recordings from my Prime. Every single one of the recordings is 720p, which I thought was a bit strange. Investigating further, it appears that using opendct.consumer.FFmpegTransSageTVConsumerImpl converts any 1080i content to 720p, unless I am mistaken. Is this correct, and is there a way to preserve the source resolution?

[trk2]

It's been a long time since I've messed around with OpenDCT settings but my memory is that opendct.consumer.FFmpegTransSageTVConsumerImpl simply remuxes unless you specify a profile. Perhaps you have specified a profile?

[jwittkoski]

From the docs for FFmpegTransSageTVConsumerImpl:

The transcoding profiles are per capture device and are not set by default. When no transcoding profile is set, the stream is only remuxed.

This matches what I see in my setup - I use FFmpegTransSageTVConsumerImpl by default but have no specific transcoding profiles defined. I see both 720 and 1080 recording from my devices, depending on the source.

Check if you have anything in your opendct.properties file that defines a transcoding profile (i.e. sagetv.device.<unique_id>.transcode_profile=ultrafast720p). Profiles are defined in C:\ProgramData\OpenDCT\config\transcode on Windows and /etc/opendct/conf/transcode on Linux.

[KeithAbb0tt]

OK, so maybe it's not my OpenDCT settings after all. It appears that the vast majority of the channels from my cable provider are broadcast in 720p; it took me a long time to find one that broadcast in 1080i. I was viewing the channels thru VLC directly from my Primes, completely bypassing OpenDCT. Once I found one, I viewed it from within SageTV and it shows as 1080p@30fps, which I'm thinking is just another way to say 1080i. Mystery solved?