Sort options by name, review formatting, apply consistency fixes and
fill the gaps (e.g. missing value for constants or flags), and review
and extend content.
Signed-off-by: Marth64 <marth64@proxyid.net>
Raw Captions With Time (RCWT) is a format native to ccextractor, a commonly
used open source tool for processing 608/708 closed caption (CC) sources.
It can be used to archive the original, raw CC bitstream and to produce
a source file file for later CC processing or conversion. As a result,
it also allows for interopability with ccextractor for processing CC data
extracted via ffmpeg. The format is simple to parse and can be used
to retain all lines and variants of CC.
A free specification of RCWT can be found here:
https://github.com/CCExtractor/ccextractor/blob/master/docs/BINARY_FILE_FORMAT.TXT
This muxer implements the specification as of 01/05/2024, which has
been stable and unchanged for 10 years as of this writing.
This muxer will have some nuances from the way that ccextractor muxes RCWT.
No compatibility issues when processing the output with ccextractor
have been observed as a result of this so far, but mileage may vary
and outputs will not be a bit-exact match.
Specifically, the differences are:
(1) This muxer will identify as "FF" as the writing program identifier, so
as to be honest about the output's origin.
(2) ffmpeg's MPEG-1/2, H264, HEVC, etc. decoders extract closed captioning
data differently than ccextractor from embedded SEI/user data.
For example, DVD captioning bytes will be translated to ATSC A53 format.
This allows ffmpeg to handle 608/708 in a consistant way downstream.
This is a lossless conversion and the meaningful data is retained.
(3) This muxer will not alter the extracted data except to remove invalid
packets in between valid CC blocks. On the other hand, ccextractor
will by default remove mid-stream padding, and add padding at the end
of the stream (in order to convey the end time of the source video).
Move section to the top of the file, use table in place of subsection
to list the comprising muxers, and show media type information and
extensions in the item entry names.
New option can be used to avoid creating very short segments with inputs
whose GOP size is variable or unharmonic with segment_time.
Only effective with segment_time.
Add PCR at keyframe can be undesirable when -pcr_period is
specified. Add an flag to disable this behavior.
Signed-off-by: Zhao Zhili <zhilizhao@tencent.com>
This allows for wider compatibility with older devices, such as those
running iOS 3. The only difference between HLS version 2 and version 3 is
that version 3 supports non-integer EXTINF values, and as such, we can
default to version 2 if we're using whole-integer EXTINFs anyways, when
`-hls_flags round_durations` is set.
As this code seems to otherwise consistently use the lowest compatible
version, this seems to fit in properly with existing behavior.
Testing confirms with that this patch, HLS output can work all the way back
to iOS 3.
Reviewed-by: Steven Liu <liuqi05@kuaishou.com>
Signed-off-by: Lucy <lucy@absolucy.moe>
This is similar to the faststart option of the mov muxer, yet
in contrast to it it works together with reserve_index_space
(the equivalent to reserved_moov_size): If the reserved space
does not suffice, the data is shifted; if not, the Cues are
written at the front without shifting the data.
Several tests that cover (not only) this have been added.
Implements #7017.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Because the hls_ts_options will be misunderstand by user,
and then user can use hls_segment_options instead of hls_ts_options.
Signed-off-by: Steven Liu <liuqi05@kuaishou.com>
