XAVC-L/S - .mxf to .mp4 re wrap

[Cliff Totten]

As the owner of several XAVC-S and L products, I can certainly say that I strongly prefer the more universal .mp4 container format. I'm not sure why but the h.264 CODEC unpacks and plays out much easier on every PC I use with it. Mxf works somewhat "ok" I guess, but for me, it's just a more noticeable pain in the butt. .Mp4 4k?...smooooooth as silk.

Question: Anybody know of a mxf to MP4 converter that extracts the h,264 stream and re wraps it into .mp4? It's very important that it not "transcode" the stream. I do not want a recompression generation loss...just an unpack and a repack. Hopefully a PC tool.

CT

[Jack Zhang]

FFmpeg in a perfect world would do it, but XDCAM codecs use a special wrapping method to embed PCM audio into a MP4 container.

Keep in mind when you remux to .MP4, you lose XAVC-L's decoding metadata to instruct the decoder to behave a certain way to reduce generation loss, hence why the MP4 XAVC-S runs better, but is inferior in image quality.

[Cliff Totten]

Ok. So you have me very curious now. When you talk about playing back the h.264 CODEC in both XAVC-L&S, you mention metadata altering the players H.264 decoder? I'm not understanding this. Can you help me out with that?

It's important to understand that both XAVC-S & L use 100% h.264 compliant encoding/decoding. There ere no Sony proprietary tools or mathematics inside that h.264. ( they have a cool patented TWO PASS look ahead VBR technology but no additional calculations that go outside MPEG standards. How they "pack" that CODEC could be propriatary.

[Jack Zhang]

It's not in the codec. For the MXF XAVC-L, it's packed as a metadata stream alongside the H.264 stream. A XAVC compliant decoder would look for that data then behave based on the metadata in the MXF stream it sees. Taking that away would decrease how well the footage holds up to generational changes.

[Cliff Totten]

What is in this mxf metadata that affects the decoder and the stream like this? (De blocking filter flag?)

Sorry man. I'm still confused,

[Ilya Spektor]

Originally Posted by Cliff Totten

As the owner of several XAVC-S and L products, I can certainly say that I strongly prefer the more universal .mp4 container format. I'm not sure why but the h.264 CODEC unpacks and plays out much easier on every PC I use with it. Mxf works somewhat "ok" I guess, but for me, it's just a more noticeable pain in the butt. .Mp4 4k?...smooooooth as silk.

Question: Anybody know of a mxf to MP4 converter that extracts the h,264 stream and re wraps it into .mp4? It's very important that it not "transcode" the stream. I do not want a recompression generation loss...just an unpack and a repack. Hopefully a PC tool.

CT

I tried TMPGEnc MPEG Smart Renderer 5.0. It gives you the option to output 4K XAVC-L mxf clips (connected or individually) to mp4 container, It gives you though a warning that XAVC-L files are an Open GOP, so not every player would play them. Anyway, VLC can play them. Interestingly enough, XAVC-L HD 10-bit clips don't have an option to be output to MP4 - only to MPEG (MPG or TS container) or MKV (MKV container)... May be, it is 8-bit vs. 10-bit depth...

[Jack Zhang]

Originally Posted by Cliff Totten

What is in this mxf metadata that affects the decoder and the stream like this? (De blocking filter flag?)

Sorry man. I'm still confused,

Look up the "XAVC Pre-coding mechanism."

Once again, a standard MP4 container cannot contain PCM audio. Sony modified the standard to contain PCM audio for XDCAM.