What is being used to Decode?

[tb582]

I have a transcoding program say Sorenson Squeeze - I drop an .mp4 (h.264) file into it to transcode to flv how can I tell what decoder squeeze is going to use to decode the mp4?

[Cornucopia]

Depends on the program.

It would either be:
1. Its own decoder.
2. Quicktime's
3. Directshow's (in which case, there may be a choice)
4. 3rd party specific decoder
<<<edit>>>>
5. VFW (older version that Directshow replaced)
<<</edit>>>


For squeeze (considering it's history), I'd think either #1 or #2.

You could try running Graphedit to see how its flow is...

BTW, why does it matter? Squeeze usually does a VERY good job of decoding (and fairly good job of encoding).

Scott

[tb582]

yeah squeeze does a good job, but we are having sync issues when using Rohzet and I want to compair what squeeze is using to decode vs Rhozet.... Tomorrow I'll try that app.

[tb582]

Depends on the program.

You could try running Graphedit to see how its flow is...

Scott

Must not be compatible with h.264 files or mp4's as it doesn't see them when I go to open the file. I was able to get it to work on an mpeg but that doesn't really help

[poisondeathray]

You need both a splitter and a decoder for directshow to render. You are probably missing a splitter (e.g. haali media splitter). Some splitters won't appear in the filter chain, but you will see them in the icon taskbar when the video is rendered

As for a decoder, the most common direct show decoder is ffdshow. Just "turn on" h264 in the ffdshow configuration from "disabled" to "libavcodec"

In GraphStudio or GraphEdit:
File=>Render media file

You can also use media players that are independent of directshow filters installed on your system (e.g. VLC, Mplayer) and these will render with their own internal filters. You could then view properties and see what they are using to render (it might be different from each other, and what is on your system for direct show)

[tb582]

You need both a splitter and a decoder for directshow to render. You are probably missing a splitter (e.g. haali media splitter). Some splitters won't appear in the filter chain, but you will see them in the icon taskbar when the video is rendered

As for a decoder, the most common direct show decoder is ffdshow. Just "turn on" h264 in the ffdshow configuration from "disabled" to "libavcodec"

In GraphStudio or GraphEdit:
File=>Render media file

You can also use media players that are independent of directshow filters installed on your system (e.g. VLC, Mplayer) and these will render with their own internal filters. You could then view properties and see what they are using to render (it might be different from each other, and what is on your system for direct show)

I dont understand, why do I need a splitter just so that GraphEdit can read the file?

[poisondeathray]

It's not a splitter in the sense of cutting a video into temporal segments.

I mean a media splitter as in video/audio splitting to feed into a decoder. You cannot render a video (at least in direct show) without a splitter. You must have had a MPEG2 splitter installed in order to view that previous video. Similarly, you must have a .mp4 splitter to render a .mp4



Note this is how you render a file in directshow (for playback, or directshow based encoding). It doesn't necessarily mean these are the filters used in encoding - that would depend on your specific application as Cornucopia alluded to.

[Cornucopia]

Think of a "splitter" more like a "container unwrapper" (incl. DEMUXER).

Scott

[tb582]

OK thanks for the explaination... but does the spitter only allow Graphedit to read the file? I mean I can play the h.264 file in vlc and quicktime, just can't open it in GraphEdit

[poisondeathray]

This was already mentioned...

Again, a splitter (along with a decoder) is required for all Direct Show applications to decode videos. I guessed earlier that you might be missing a splitter.

vlc and quicktime aren't based on Direct Show filters on your system (at least not directly) - they have their own internal codecs and splitters - so they play back fine on your system

Players like MPC, Mplayer are based on Direct Show. Graph Edit and Graph Studio are used as tools for Direct Show to show what filters are currently being used

Again, what filter is used to decode or encode is dependent on the application. I'm guessing Squeeze is using Direct Show file (not one of the other systems that Cornucopia mentioned) to decode the original file then output to whatever...

[Ai Haibara]

It would also help players that use DirectShow to play files, such as Windows Media Player, and Media Player Classic.

poisondeathray: I thought mplayer used its own codecs/etc. (whatever support you have installed for mplayer), not DirectShow?

[poisondeathray]

poisondeathray: I thought mplayer used its own codecs/etc. (whatever support you have installed for mplayer), not DirectShow?

Yes, my mistake. I actually said that my 1st response, and then contradicted myself in the most recent response My 1st response was correct, it is like VLC, sorry for the mixup

[tb582]

ok I was able to open the file in GraphEdit and its flow is the same as the origianl file that is in sync, is there any way to tell what the program thats doing the transcode is using to decode the video before it transcodes?