[FFmpeg-user] Question about file size changes
d.shuman at att.net
Sat Jun 22 11:07:28 EEST 2019
MediaInfo may not be good for some things but it does appear to identify the details of the closed captioning streams/content? better than ffmpeg or ffprobe have with the options I have found to date.
In this case it also appears to have identified (for me at least) a conversion from BDAV to mpegts because of a file suffix (mts) suggesting the prefix to be invalid triggered a web search by me that suggested a means to prevent that conversion (by changing the file type to m2ts). MediaINFO appears to have confirmed for me that the m2ts suffix prevented the change from BDAV to mpegts.
This statement "When you remux, you cannot change the quality of the media in the file, this is simply not possible." confuses me because this statement "While there is indeed some BDAV writing support in the mpegts muxer, I don't think it is complete." Seems to indicate a remux operation that changes from BDAV to mpegts may use incomplete BDAV interpretation code that may not be as good as a remux that maintains BDAV on both sides.
If I understand "While there is indeed some BDAV writing support in the mpegts muxer, I don't think it is complete." as noted above you appear to indicate that the conversion of the file suffix to m2ts should deliver either equivalent or better results by eliminating the change from BDAV to mpegts caused by the mts file suffix. Thanks this appears to be the answer I was seeking.
Do I understand what you wrote?
On Wednesday, June 19, 2019, 10:27:08 AM EDT, Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:
Am Mi., 19. Juni 2019 um 02:54 Uhr schrieb David Shuman <d.shuman at att.net>:
> In terms of which conversion is more valid which play quality would be
> closer to the original -- does the m2ts change less of the content when
> remixing than the mts as BDAV does not change to mpeg-ts our would
> one consider the additional headers from m2ts to more of a quality
> change so mts provides a file more like the original again in terms of
> play quality?
There are several misunderstandings in this thread, I will try to explain
some of them (and repeat other explanations):
When you remux, you cannot change the quality of the media in the file,
this is simply not possible.
FFmpeg is not a file editor, so contrary to what some comments here
imply, you simply cannot remux and expect that the resulting file is
very similar to the original file, with only the changes you wanted. On
the contrary, the output file is always a new file with new properties,
some of them will be identical to the original file, others won't.
You already know that MediaInfo is not an ideal tool to find issues in
While there is indeed some BDAV writing support in the mpegts muxer,
I don't think it is complete.
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