[FFmpeg-devel] [PATCH v3 4/6] avcodec/rcwtenc: canonize name and refresh documentation

Marth64 marth64 at proxyid.net
Tue Mar 12 08:00:03 EET 2024


The formal title of the muxer according to the specification
is "RCWT (Raw Captions With Time)", so canonize this
in the long name of the codec and docs.

In the documentation section, point #2 was wrong: ccextractor
extracts the Closed Captions data and stores normalized bits
similarly to this muxer.

Signed-off-by: Marth64 <marth64 at proxyid.net>
---
 libavformat/rcwtenc.c | 21 +++++++--------------
 1 file changed, 7 insertions(+), 14 deletions(-)

diff --git a/libavformat/rcwtenc.c b/libavformat/rcwtenc.c
index a6060ba7c4..ed72de81ef 100644
--- a/libavformat/rcwtenc.c
+++ b/libavformat/rcwtenc.c
@@ -1,6 +1,5 @@
 /*
- * Raw Captions With Time (RCWT) muxer
- * Author: Marth64 <marth64 at proxyid.net>
+ * RCWT (Raw Captions With Time) muxer
  *
  * This file is part of FFmpeg.
  *
@@ -20,16 +19,16 @@
  */
 
 /*
- * 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.
+ * RCWT (Raw Captions With Time) is a format native to ccextractor, a commonly
+ * used open source tool for processing 608/708 Closed Captions (CC) sources.
  * It can be used to archive the original, raw CC bitstream and to produce
  * a source 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.
  *
- * This muxer implements the specification as of 2024-01-05, which has
- * been stable and unchanged for 10 years as of this writing.
+ * This muxer implements the specification as of March 2024, which has
+ * been stable and unchanged since April 2014.
  *
  * This muxer will have some nuances from the way that ccextractor muxes RCWT.
  * No compatibility issues when processing the output with ccextractor
@@ -40,13 +39,7 @@
  * (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
+ * (2) 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).
@@ -172,7 +165,7 @@ static int rcwt_write_trailer(AVFormatContext *avf)
 
 const FFOutputFormat ff_rcwt_muxer = {
     .p.name             = "rcwt",
-    .p.long_name        = NULL_IF_CONFIG_SMALL("Raw Captions With Time"),
+    .p.long_name        = NULL_IF_CONFIG_SMALL("RCWT (Raw Captions With Time)"),
     .p.extensions       = "bin",
     .p.flags            = AVFMT_GLOBALHEADER | AVFMT_VARIABLE_FPS | AVFMT_TS_NONSTRICT,
     .p.subtitle_codec   = AV_CODEC_ID_EIA_608,
-- 
2.34.1



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