[FFmpeg-devel] [PATCH] avformat/hlsenc: limit segments count to search duplicated segments filenames

[FFmpeg-devel] [PATCH] avformat/hlsenc: limit segments count to search duplicated segments filenames

[Artem Smorodin]

This linear search has a complexity of O(n). When ffmpeg attempts to 
parse a playlist containing approximately 100,000 segments, it 
effectively causes a hang for several minutes.

This patch limits the allowed size for duplicate searches to a 
reasonable value. Now it takes between 0.5 and a few seconds (tested on 
different devices) instead of several minutes.

Signed-off-by: Artem Smorodin <artem.smorodin@dacast.com>
---
  libavformat/hlsenc.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavformat/hlsenc.c b/libavformat/hlsenc.c
index a93d35ab75..d3db83093c 100644
--- a/libavformat/hlsenc.c
+++ b/libavformat/hlsenc.c
@@ -1172,7 +1172,7 @@ static int hls_append_segment(struct 
AVFormatContext *s, HLSContext *hls,
      if (hls->use_localtime_mkdir) {
          filename = vs->avf->url;
      }
-    if ((find_segment_by_filename(vs->segments, filename) || 
find_segment_by_filename(vs->old_segments, filename))
+    if (vs->nb_entries <= 5000 && 
(find_segment_by_filename(vs->segments, filename) || 
find_segment_by_filename(vs->old_segments, filename))
          && !byterange_mode) {
          av_log(hls, AV_LOG_WARNING, "Duplicated segment filename 
detected: %s\n", filename);
      }
-- 
2.43.0

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Re: [FFmpeg-devel] [PATCH] avformat/hlsenc: limit segments count to search duplicated segments filenames

[Michael Niedermayer]

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On Sat, Jul 26, 2025 at 07:09:54PM +0300, Artem Smorodin wrote:
> This linear search has a complexity of O(n). When ffmpeg attempts to parse a
> playlist containing approximately 100,000 segments, it effectively causes a
> hang for several minutes.
> 
> This patch limits the allowed size for duplicate searches to a reasonable
> value. Now it takes between 0.5 and a few seconds (tested on different
> devices) instead of several minutes.
> 
> Signed-off-by: Artem Smorodin <artem.smorodin@dacast.com>
> ---
>  libavformat/hlsenc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

will apply

thx

[...]
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