Commit graph

20 commits

Author SHA1 Message Date
Chris Bass
d25be0d16e ttmlparse: Handle whitespace before XML declaration
When ttmlparse is in, e.g., an MPEG-DASH pipeline, there may be
whitespace between successive TTML documents in ttmlparse's accumulated
input. As libxml2 will fail to parse documents that have whitespace
before the opening XML declaration, ensure that any preceding whitespace
is not passed to libxml2.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/1539>
2020-10-30 07:01:52 +00:00
Chris Bass
8df2314c23 ttmlparse: Ensure only single TTML doc parsed
The parser handles only one TTML file at a time, therefore if there are
multiple TTML documets in the input, parse only the first.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/1539>
2020-10-30 07:01:52 +00:00
Seungha Yang
ae76f9ab23 ttmlparse: Collect buffers until detecting complete xml document
Given buffer could be fragmented and we might need to
collect buffers until end tag is detected. And/or, a buffer
can consist of multiple ttml documents.

Fixes: https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/issues/494
2019-11-22 18:31:10 +09:00
Aaron Boxer
6d3429af34 documentation: fixed a heap o' typos 2019-11-05 09:11:25 -05:00
Chris Bass
2863a55a89 ttml: Add support for IMSC 1.0.1 fillLineGap attribute
Strictly speaking, the TTML spec requires that text backgrounds extend
only to the font height of the related text, rather than to the vertical
distance between lines. The result of this is that there will typically
be vertical gaps between line backgrounds through which moving video can
be seen. Since this was unnacceptable to some content providers, v1.0.1
of the IMSC spec (which profiles TTML) adds a new attribute,
itts:fillLineGap[1], that allows content authors to specify that clients
should extend text backgrounds such that there are no gaps between
lines. This attribute is also going to be included in the next release
of EBU-TT-D.

This patch adds support for fillLineGap to ttmlparse and ttmlrender.

[1] https://www.w3.org/TR/ttml-imsc1.0.1/#itts-fillLineGap

https://bugzilla.gnome.org/show_bug.cgi?id=787071
2018-02-27 16:27:47 +02:00
Chris Bass
3d2f004db2 ttmlparse: Ensure default showBackground behaviour is enacted
Ensure that region backgrounds are always show when tts:showBackground
is not explicitly set, in accordance with the default behavour given in
the TTML spec.

https://bugzilla.gnome.org/show_bug.cgi?id=787942
2017-09-20 17:11:29 +03:00
Edward Hervey
417c70805b ttml: Simplify code
n2 can never be NULL since:
* it's in a "while (n1 && n2)" block
* and it's not modified before

CID #1405868
2017-05-26 17:55:44 +02:00
Chris Bass
acfaf3a001 ttmlparse: Consolidate adjacent co-styled inline elements
A common subtitling use case is live-generated subtitles, in which each
new word is contained in its own span, and the spans are displayed
sequentially, with the effect that lines of displayed subtitles are
built up word-by-word.

This can, however, cause problems when the number of words in a block is
greater than the number of allowed GstMemorys in a GstBuffer.

Since in this use case each span will have the same styling as adjacent
spans, we can join adjacent spans (and other inline elements, such as
breaks) into a single element containing the concatenated text of each,
thus avoiding the limit of GstMemorys in a GstBuffer and also reducing
the amount of styling/layout metadata that is attached to each buffer.

https://bugzilla.gnome.org/show_bug.cgi?id=781725
2017-04-25 22:18:53 +03:00
Chris Bass
22c3830858 ttmlparse: Don't add GstMemorys to a GstBuffer that is full
The parser stores the text from each inline element of a scene in its
own GstMemory, which is inserted in the GstBuffer containing the scene
data. However, GstBuffers can contain only a limited number of
GstMemorys. Therefore, don't add more than the maximum number of
GstMemorys to each buffer, and warn if this is attempted.

https://bugzilla.gnome.org/show_bug.cgi?id=781725
2017-04-25 22:18:53 +03:00
Chris Bass
ef65230b46 ttmlparse: Store newline as text of br element
When parsing <br> elements, store an actual newline in the text field of
the created TtmlElement. They then don't need to be treated as a
separate case from anon-span elements when being processed.

https://bugzilla.gnome.org/show_bug.cgi?id=781725
2017-04-25 22:18:53 +03:00
Chris Bass
81157e5168 ttmlparse: Replace repeated warning code with a function.
Encapsulates in a function the code that warns of an illegally
positioned element, rather than repeating the same code multiple times.
Also frees a string allocated by ttml_get_element_type_string, which was
previously being leaked.

https://bugzilla.gnome.org/show_bug.cgi?id=781725
2017-04-25 22:18:53 +03:00
Chris Bass
8b19cccfc5 ttmlparse: Remove redundant text_index field of TtmlElement
https://bugzilla.gnome.org/show_bug.cgi?id=781725
2017-04-25 22:18:53 +03:00
Chris Bass
d8afce67c3 ttmlparse: Don't leak TtmlElements when deleting GNodes/trees.
https://bugzilla.gnome.org/show_bug.cgi?id=781725
2017-04-25 22:18:53 +03:00
Chris Bass
9f5e41218f ttmlparse: Convert tabs to spaces in input
The TTML spec has an issue in which tab (U+0009) characters that are
first in a sequence of whitespace characters are not suppressed at the
start and end of line areas. This issue was reported in [1] and the
editor of the TTML specs confirmed that this was not the intention
behind the spec.

The editor has created an issue to fix this in both the TTML1 and TTML2
specs [2], giving a proposal of what the spec should say. This patch
updates ttmlparse to implement the intended behaviour as proposed, in
which tabs in the input are converted to spaces before processing.

[1] https://github.com/w3c/imsc/issues/224
[2] https://github.com/w3c/ttml1/issues/235

https://bugzilla.gnome.org/show_bug.cgi?id=781539
2017-04-20 18:50:05 +01:00
Chris Bass
6eb36406f0 ttmlparse: Fix potential resource leak identified by coverity.
If multiple styles/regions with the same ID are present in the input
(which is not allowed in TTML), use the last and give a warning.

Fixes CID #1405134.
2017-04-20 10:40:32 +01:00
Chris Bass
98ce1e11bc ttmlparse: Fix potential NULL dereference identified by coverity
Hopefully fixes CID #1405131.
2017-04-19 18:28:31 +01:00
Chris Bass
b4d9d9d9f8 ttmlparse: don't filter out untimed whitespace
Significant whitespace in elements that don't have begin/end values
should inherit timing from its parent, or if no its parents have no
timing, from the document's Root Temporal Extent. Currently, such
whitespace is removed, which is not spec-compliant. Fix this by
retaining whitespace in content nodes, and assigning a Root Temporal
Extent of 24 hours to any significant whitespace whose parents have no
associated timing.

https://bugzilla.gnome.org/show_bug.cgi?id=781027
2017-04-09 10:42:16 +03:00
Chris Bass
0288ee24e9 ttml: correctly implement lineHeight behaviour
The specified behaviour in TTML when lineHeight is "normal" is different
from the behaviour when a percentage is given. In the former case, the
line height is a percentage (the TTML spec recommends 125%) of the largest
font size that is applied to the spans within the block; in the latter
case, the line height is the given percentage of the font size that is
applied to the block itself.

The code doesn't correctly implement this behaviour; this patch fixes
that.

https://bugzilla.gnome.org/show_bug.cgi?id=780402
2017-04-09 10:42:08 +03:00
Chris Bass
4ac2a8d6a6 ttml: Replace assertions
Remove assertions and replace, where necessary, with code that handles
the error cases.

https://bugzilla.gnome.org/show_bug.cgi?id=776436
2017-03-15 13:28:36 +02:00
Chris Bass
d82ae6949f ttml: Add plugin that supports TTML subtitles
Add a parser (ttmlparse) and renderer (ttmlrender) element that handle
subtitles that use the EBU-TT-D profile of TTML1.

https://bugzilla.gnome.org/show_bug.cgi?id=758232
2016-11-01 20:46:46 +02:00