On 12/25/24 3:46 AM, Wang Bin wrote:
On 12/19/24 3:59 AM, Wang Bin wrote:
based on Hendrik Leppkes's fork
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This patch has a big web of gotos. This can get very confusing. Is there
any way to change it so there's if blocks or other static functions to
call? Gotos should be used very sparingly and mostly to goto the end of
a block where cleanup happens.
- Leo Izen (Traneptora)
From 5bd4a6f56231c3160be6c2d322f5d1081d7b3622 Mon Sep 17 00:00:00 2001
From: wang-bin <wbse...@gmail.com>
Date: Tue, 17 Dec 2024 23:21:57 +0800
Subject: [PATCH] matroskadec: support S_TEXT/WEBVTT
fix ticket #5641
---
libavformat/matroska.c | 1 +
libavformat/matroskadec.c | 102 ++++++++++++++++++++++----------------
2 files changed, 60 insertions(+), 43 deletions(-)
diff --git a/libavformat/matroska.c b/libavformat/matroska.c
index d0ecfbeb6a..23c4ad6949 100644
--- a/libavformat/matroska.c
+++ b/libavformat/matroska.c
@@ -63,6 +63,7 @@ const CodecTags ff_mkv_codec_tags[]={
{"D_WEBVTT/CAPTIONS" , AV_CODEC_ID_WEBVTT},
{"D_WEBVTT/DESCRIPTIONS", AV_CODEC_ID_WEBVTT},
{"D_WEBVTT/METADATA" , AV_CODEC_ID_WEBVTT},
+ {"S_TEXT/WEBVTT" , AV_CODEC_ID_WEBVTT},
{"S_TEXT/UTF8" , AV_CODEC_ID_SUBRIP},
{"S_TEXT/UTF8" , AV_CODEC_ID_TEXT},
diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c
index 0e150f9138..11af2cface 100644
--- a/libavformat/matroskadec.c
+++ b/libavformat/matroskadec.c
@@ -3761,68 +3761,83 @@ static int matroska_parse_prores(MatroskaTrack
*track,
return 0;
}
+static int matroska_webvtt_read_line(uint8_t** begin, uint8_t* end)
static ptrdiff_t matroska_webvtt_read_line(const uint8_t **begin, const
uint8_t *end)
+{
+ uint8_t *p = *begin;
+ int len = -1;
ptrdiff_t len = -1;
+
+ while (p < end) {
+ if (*p == '\r' || *p == '\n') {
+ len = p - *begin;
+ if (*p == '\r')
+ p++;
This will cause AVERROR_INVALIDDATA to return, if a \r is found without
a \n after it. Is this intentional?
+ break;
+ }
+ p++;
+ }
+
+ if (p >= end || *p != '\n')
+ return AVERROR_INVALIDDATA;
+ p++;
+ *begin = p;
These two lines can be replaced with: *begin = p + 1;
+ return len;
+}
+
static int matroska_parse_webvtt(MatroskaDemuxContext *matroska,
MatroskaTrack *track,
AVStream *st,
uint8_t *data, int data_len,
+ MatroskaBlockMore *blockmore, int
nb_blockmore,
uint64_t timecode,
uint64_t duration,
int64_t pos)
{
AVPacket *pkt = matroska->pkt;
uint8_t *id, *settings, *text, *buf;
- int id_len, settings_len, text_len;
+ int id_len = -1, settings_len = -1, text_len = -1;
ptrdiff_t id_len, settings_le, text_len;
This are never read uninitialized.
uint8_t *p, *q;
int err;
+ const int webm_style = !strncmp(track->codec_id, "D_WEBVTT/", 9);
if (data_len <= 0)
return AVERROR_INVALIDDATA;
- p = data;
- q = data + data_len;
-
- id = p;
- id_len = -1;
- while (p < q) {
- if (*p == '\r' || *p == '\n') {
- id_len = p - id;
- if (*p == '\r')
- p++;
- break;
+ if (webm_style) {
+ p = data;
+ q = data + data_len;
+ id = p;
+ id_len = matroska_webvtt_read_line(&p, q);
+ if (id_len < 0)
+ return AVERROR_INVALIDDATA;
+ settings = p;
+ settings_len = matroska_webvtt_read_line(&p, q);
+ if (settings_len < 0)
+ return AVERROR_INVALIDDATA;
+ text = p;
+ text_len = data + data_len - p;
+ while (text_len > 0) {
+ const int len = text_len - 1;
+ const uint8_t c = p[len];
+ if (c != '\r' && c != '\n')
+ break;
+ text_len = len;
}
You can replace this loop with:
while (text_len-- > 0 && (p[text_len] == '\r' || p[text_len] == '\n')) {
// empty
}
text_len++;
The lazy && ensures that text_len-- is evaluated before p[text_len] is
dereferenced.
- p++;
- }
-
- if (p >= q || *p != '\n')
- return AVERROR_INVALIDDATA;
- p++;
-
- settings = p;
- settings_len = -1;
- while (p < q) {
- if (*p == '\r' || *p == '\n') {
- settings_len = p - settings;
- if (*p == '\r')
- p++;
- break;
+ } else {
+ if (nb_blockmore > 0) {
} else if (nb_blockmore > 0) {
+ p = blockmore->additional.data;
+ q = p + blockmore->additional.size;
+ settings = p;
+ settings_len = matroska_webvtt_read_line(&p, q);
+ if (settings_len < 0)
+ return AVERROR_INVALIDDATA;
+ id = p;
+ id_len = matroska_webvtt_read_line(&p, q);
+ if (id_len < 0)
+ return AVERROR_INVALIDDATA;
}
- p++;
- }
-
- if (p >= q || *p != '\n')
- return AVERROR_INVALIDDATA;
- p++;
-
- text = p;
- text_len = q - p;
- while (text_len > 0) {
- const int len = text_len - 1;
- const uint8_t c = p[len];
- if (c != '\r' && c != '\n')
- break;
- text_len = len;
+ text = data;
+ text_len = data_len;
}
-
if (text_len <= 0)
return AVERROR_INVALIDDATA;
@@ -4215,6 +4230,7 @@ static int
matroska_parse_block(MatroskaDemuxContext *matroska, AVBufferRef *buf
} else if (st->codecpar->codec_id == AV_CODEC_ID_WEBVTT) {
res = matroska_parse_webvtt(matroska, track, st,
out_data, out_size,
+ blockmore, nb_blockmore,
timecode, lace_duration,
pos);
if (!buf)
Overall it's a lot cleaner and easier to read though.
- Leo Izen (Traneptora)
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