[FFmpeg-devel] [PATCH 1/2] avformat/format: Stop reading data at EOF during probing

[FFmpeg-devel] [PATCH 1/2] avformat/format: Stop reading data at EOF during probing

[Michael Niedermayer]

Issue found by: Сергей Колесников
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavformat/format.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/libavformat/format.c b/libavformat/format.c
index 76f25ab5a6..52b814e67d 100644
--- a/libavformat/format.c
+++ b/libavformat/format.c
@@ -231,6 +231,7 @@ int av_probe_input_buffer2(AVIOContext *pb, const AVInputFormat **fmt,
     int ret = 0, probe_size, buf_offset = 0;
     int score = 0;
     int ret2;
+    int eof = 0;
 
     if (!max_probe_size)
         max_probe_size = PROBE_BUF_MAX;
@@ -254,7 +255,7 @@ int av_probe_input_buffer2(AVIOContext *pb, const AVInputFormat **fmt,
         }
     }
 
-    for (probe_size = PROBE_BUF_MIN; probe_size <= max_probe_size && !*fmt;
+    for (probe_size = PROBE_BUF_MIN; probe_size <= max_probe_size && !*fmt && !eof;
          probe_size = FFMIN(probe_size << 1,
                             FFMAX(max_probe_size, probe_size + 1))) {
         score = probe_size < max_probe_size ? AVPROBE_SCORE_RETRY : 0;
@@ -270,6 +271,7 @@ int av_probe_input_buffer2(AVIOContext *pb, const AVInputFormat **fmt,
 
             score = 0;
             ret   = 0;          /* error was end of file, nothing read */
+            eof   = 1;
         }
         buf_offset += ret;
         if (buf_offset < offset)
-- 
2.17.1

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[FFmpeg-devel] [PATCH 2/2] avformat/hls: reduce default max reload to 100

[Michael Niedermayer]

The 1000 did result in a apparent never ending reload loop

Issue found by: Сергей Колесников
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavformat/hls.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavformat/hls.c b/libavformat/hls.c
index 11e345b280..77bce8fc0d 100644
--- a/libavformat/hls.c
+++ b/libavformat/hls.c
@@ -2556,7 +2556,7 @@ static const AVOption hls_options[] = {
         {.str = "3gp,aac,avi,ac3,eac3,flac,mkv,m3u8,m4a,m4s,m4v,mpg,mov,mp2,mp3,mp4,mpeg,mpegts,ogg,ogv,oga,ts,vob,wav"},
         INT_MIN, INT_MAX, FLAGS},
     {"max_reload", "Maximum number of times a insufficient list is attempted to be reloaded",
-        OFFSET(max_reload), AV_OPT_TYPE_INT, {.i64 = 1000}, 0, INT_MAX, FLAGS},
+        OFFSET(max_reload), AV_OPT_TYPE_INT, {.i64 = 100}, 0, INT_MAX, FLAGS},
     {"m3u8_hold_counters", "The maximum number of times to load m3u8 when it refreshes without new segments",
         OFFSET(m3u8_hold_counters), AV_OPT_TYPE_INT, {.i64 = 1000}, 0, INT_MAX, FLAGS},
     {"http_persistent", "Use persistent HTTP connections",
-- 
2.17.1

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Re: [FFmpeg-devel] [PATCH 2/2] avformat/hls: reduce default max reload to 100

[Paul B Mahol]

On Wed, May 10, 2023 at 11:58 PM Michael Niedermayer <michael@niedermayer.cc>
wrote:

> The 1000 did result in a apparent never ending reload loop
>
>
How so? Somewhere overflow happens causing infinity?



> Issue found by: Сергей Колесников
> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> ---
>  libavformat/hls.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/libavformat/hls.c b/libavformat/hls.c
> index 11e345b280..77bce8fc0d 100644
> --- a/libavformat/hls.c
> +++ b/libavformat/hls.c
> @@ -2556,7 +2556,7 @@ static const AVOption hls_options[] = {
>          {.str =
> "3gp,aac,avi,ac3,eac3,flac,mkv,m3u8,m4a,m4s,m4v,mpg,mov,mp2,mp3,mp4,mpeg,mpegts,ogg,ogv,oga,ts,vob,wav"},
>          INT_MIN, INT_MAX, FLAGS},
>      {"max_reload", "Maximum number of times a insufficient list is
> attempted to be reloaded",
> -        OFFSET(max_reload), AV_OPT_TYPE_INT, {.i64 = 1000}, 0, INT_MAX,
> FLAGS},
> +        OFFSET(max_reload), AV_OPT_TYPE_INT, {.i64 = 100}, 0, INT_MAX,
> FLAGS},
>      {"m3u8_hold_counters", "The maximum number of times to load m3u8 when
> it refreshes without new segments",
>          OFFSET(m3u8_hold_counters), AV_OPT_TYPE_INT, {.i64 = 1000}, 0,
> INT_MAX, FLAGS},
>      {"http_persistent", "Use persistent HTTP connections",
> --
> 2.17.1
>
> _______________________________________________
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> ffmpeg-devel@ffmpeg.org
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> ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".
>
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Re: [FFmpeg-devel] [PATCH 2/2] avformat/hls: reduce default max reload to 100

[Michael Niedermayer]

[-- Attachment #1.1: Type: text/plain, Size: 1221 bytes --]

On Thu, May 11, 2023 at 07:36:04PM +0200, Paul B Mahol wrote:
> On Wed, May 10, 2023 at 11:58 PM Michael Niedermayer <michael@niedermayer.cc>
> wrote:
> 
> > The 1000 did result in a apparent never ending reload loop
> >
> >
> How so? Somewhere overflow happens causing infinity?

no, it was lack of patience
each reload before the patches takes 50seconds with the testcase
thats with one url which returns 55 bytes
i didnt benchmark it but i would expect 1000 reloads to take
about 14 hours
after the bugfix it should be a bit less than 2 hours
and with just 100 reloads its maybe 10minutes

Why is the reload taking so long ?
The RFC says this:
"If the client reloads a Playlist file and finds that it has not
   changed, then it MUST wait for a period of one-half the target
   duration before retrying."
   
Given that i think a default of 100 is actually still too much
and something like 3 is better, so i will locally change the default
to 3   

thx

[...]
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Re: [FFmpeg-devel] [PATCH 1/2] avformat/format: Stop reading data at EOF during probing

[Michael Niedermayer]

[-- Attachment #1.1: Type: text/plain, Size: 572 bytes --]

On Wed, May 10, 2023 at 11:58:31PM +0200, Michael Niedermayer wrote:
> Issue found by: Сергей Колесников
> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> ---
>  libavformat/format.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)

will apply

[...]
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The real ebay dictionary, page 2
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