On Wed, 29 Oct 2014, Yusuke Nakamura wrote:
2014-10-29 22:00 GMT+09:00 Martin Storsjö <[email protected]>:
On Wed, 29 Oct 2014, Yusuke Nakamura wrote:
This patch produces out-of-spec files about the file format compatibility.
Fragmented files with default-base-is-moof shall not contain brands
earlier
than iso5.
I know such broken files exist e.g. DASH-IF test vectors, but the spec
clearly says that default-base-is-moof shall not be set under the earlier
brands even if moof contains only one traf.
Right, so would it be ok if I'd add something like this:
--- a/libavformat/movenc.c
+++ b/libavformat/movenc.c
@@ -2881,8 +2881,12 @@ static int mov_write_ftyp_tag(AVIOContext *pb,
AVFormatCo
ffio_wfourcc(pb, "piff");
ffio_wfourcc(pb, "iso2");
} else {
- ffio_wfourcc(pb, "isom");
- ffio_wfourcc(pb, "iso2");
+ if (mov->flags & FF_MOV_FLAG_DEFAULT_BASE_MOOF) {
+ ffio_wfourcc(pb, "iso5");
+ } else {
+ ffio_wfourcc(pb, "isom");
+ ffio_wfourcc(pb, "iso2");
+ }
if (has_h264)
ffio_wfourcc(pb, "avc1");
}
(Possibly the same also for the ISM case above.)
Still insufficient because of major_brand when mov->mode == MODE_MP4.
And "brand" option could also produce broken files.
Sure, the brand option obviously can produce anything...
So, if we are using default-base-is-moof, we should set major == iso5 and
not include any extra isom/iso2 in compatible_brands, right? But it's ok
to keep e.g. avc1 in that list?
By the way, tfdt is defined in iso6 or later brands.
So, adding iso6 brand is strongly preferable for writing tfdt by another
preceding patch.
Should we set iso6 as major_brand unconditionally when using tfdt and
remove all other iso* compatible brands as well, or is it ok to keep it as
isom and just add iso6 in the list of compatible brands? A file that uses
tfdt should be mostly playable even if a player doesn't understand tfdt
(unless the start is truncated), contrary to default-base-is-moof which
completely breaks reading by anybody who doesn't understand it.
// Martin
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