From thiele at streamline-x.org  Sat Apr  1 16:43:48 2023
From: thiele at streamline-x.org (H. Thiele)
Date: Sat, 1 Apr 2023 18:43:48 +0200
Subject: [x264-devel] [bug-report] An accidental trailing space in qpfile
 encodes as a broken I-frame
Message-ID: <fe2865a3-422f-5512-0a4b-0645c6a2c104@streamline-x.org>


Hi,

I did not find a suitable way to sign-in to your issue tracker (I only 
can log-in when I have an account with Google, Twitter, etc.?), so I 
hope it is acceptable to report my issue here on this mailing list.


Issue
-----

Having a random trailing space in a qpfile can lead to the respective 
frame encoded as a blank grey I-frame (no image content), following B/P 
frames warp then in funnily. It's quite a nice looking glitch.


e.g. an qpfile could look like this to force some i-frames on specific
scene switches (e.g. dark -> dark to aid with debanding efforts):

...
4507<space>I<newline>
4578<space>I<newline>
5414<space>I<newline>
5619<space>I<newline>
5764<space>I<newline>
5870<space>I<newline>
6113<space>I<space><newline>
12744<space>I<newline>
12799<space>I<newline>
19428<space>I<newline>
...

Please note the extra accidental space character after the "I" for frame 
#6113.

After removing the space character and re-encoding the whole file the 
issue went away.


What Should Happen?
-------------------

Accidental trailing whitespace in lines of a qpfile should be ignored 
and not trigger encoding errors.

My wild guess is it was trying to parse of the optional QP value, failed 
on it, and then set it to an internal default.


Used x264 Command Line (Example)
--------------------------------

vspipe --y4m input.vpy - | x264 --crf 17 --profile high422 --preset 
veryslow --tune film --demuxer y4m - --output output.264 --no-interlaced 
--level 4.1 --deblock -2:-2 --force-cfr --range tv --colorprim bt709 
--transfer bt709 --colormatrix bt709 --sar 1:1 --vbv-maxrate 5120 
--vbv-bufsize 12288 --threads 4 --frames 48012 --qpfile qpfile.txt



regards,
H. Thiele

From BugMaster at narod.ru  Sun Apr  2 13:24:54 2023
From: BugMaster at narod.ru (BugMaster)
Date: Sun, 2 Apr 2023 16:24:54 +0300
Subject: [x264-devel] [bug-report] An accidental trailing space in
 qpfile encodes as a broken I-frame
In-Reply-To: <fe2865a3-422f-5512-0a4b-0645c6a2c104@streamline-x.org>
References: <fe2865a3-422f-5512-0a4b-0645c6a2c104@streamline-x.org>
Message-ID: <1433626390.20230402162454@narod.ru>

On Sat, 1 Apr 2023 18:43:48 +0200, H. Thiele wrote:

> Hi,

> I did not find a suitable way to sign-in to your issue tracker (I only
> can log-in when I have an account with Google, Twitter, etc.?), so I 
> hope it is acceptable to report my issue here on this mailing list.

Hi. I don't know why they removed the link "Register now", but in
theory you can try to replace sign_in with sing_up in the url.


> Issue
> -----

> Having a random trailing space in a qpfile can lead to the respective 
> frame encoded as a blank grey I-frame (no image content), following B/P
> frames warp then in funnily. It's quite a nice looking glitch.


> e.g. an qpfile could look like this to force some i-frames on specific
> scene switches (e.g. dark -> dark to aid with debanding efforts):

> ...
> 4507<space>I<newline>
> 4578<space>I<newline>
> 5414<space>I<newline>
> 5619<space>I<newline>
> 5764<space>I<newline>
> 5870<space>I<newline>
> 6113<space>I<space><newline>
> 12744<space>I<newline>
> 12799<space>I<newline>
> 19428<space>I<newline>
> ...

> Please note the extra accidental space character after the "I" for frame
> #6113.

> After removing the space character and re-encoding the whole file the 
> issue went away.

https://code.videolan.org/videolan/x264/-/merge_requests/129 should
probably fix your issue.

> What Should Happen?
> -------------------

> Accidental trailing whitespace in lines of a qpfile should be ignored 
> and not trigger encoding errors.

> My wild guess is it was trying to parse of the optional QP value, failed
> on it, and then set it to an internal default.

It parsed 6113<space>I<space><newline>12744<space>I<newline> as
frame=6113
type=I
qp=12744 (due such high qp value it decimated to grey frame)

And later probably failed with error:
x264 [error]: can't parse qpfile for frame 6114


From gitlab at videolan.org  Sun Apr 23 17:56:21 2023
From: gitlab at videolan.org (Anton Mitrofanov (@BugMaster))
Date: Sun, 23 Apr 2023 19:56:21 +0200
Subject: [x264-devel] [Git][videolan/x264][master] Improve qpfile parsing
 resiliency
Message-ID: <644571451d663_1708881963f95c160765f@gitlab.mail>



Anton Mitrofanov pushed to branch master at VideoLAN / x264


Commits:
a8b68ebf by Anton Mitrofanov at 2023-04-02T15:51:50+03:00
Improve qpfile parsing resiliency

- - - - -


1 changed file:

- x264.c


Changes:

=====================================
x264.c
=====================================
@@ -1802,18 +1802,26 @@ static void parse_qpfile( cli_opt_t *opt, x264_picture_t *pic, int i_frame )
 {
     int num = -1;
     char type;
+    char buf[100];
     while( num < i_frame )
     {
         int64_t file_pos = ftell( opt->qpfile );
         int qp = -1;
-        int ret = fscanf( opt->qpfile, "%d %c%*[ \t]%d\n", &num, &type, &qp );
+        int ret = fscanf( opt->qpfile, " %99[^\n]\n", buf );
+        if( ret == 1 )
+        {
+            ret = sscanf( buf, "%d %c %d", &num, &type, &qp );
+            if( ret == EOF )
+                ret = 0;
+        }
         pic->i_type = X264_TYPE_AUTO;
         pic->i_qpplus1 = X264_QP_AUTO;
         if( num > i_frame || ret == EOF )
         {
-            if( file_pos < 0 || fseek( opt->qpfile, file_pos, SEEK_SET ) )
+            if( ret == EOF || file_pos < 0 || fseek( opt->qpfile, file_pos, SEEK_SET ) )
             {
-                x264_cli_log( "x264", X264_LOG_ERROR, "qpfile seeking failed\n" );
+                if( ret != EOF )
+                    x264_cli_log( "x264", X264_LOG_ERROR, "qpfile seeking failed\n" );
                 fclose( opt->qpfile );
                 opt->qpfile = NULL;
             }
@@ -1821,8 +1829,6 @@ static void parse_qpfile( cli_opt_t *opt, x264_picture_t *pic, int i_frame )
         }
         if( num < i_frame && ret >= 2 )
             continue;
-        if( ret == 3 && qp >= 0 )
-            pic->i_qpplus1 = qp+1;
         if     ( type == 'I' ) pic->i_type = X264_TYPE_IDR;
         else if( type == 'i' ) pic->i_type = X264_TYPE_I;
         else if( type == 'K' ) pic->i_type = X264_TYPE_KEYFRAME;
@@ -1837,6 +1843,8 @@ static void parse_qpfile( cli_opt_t *opt, x264_picture_t *pic, int i_frame )
             opt->qpfile = NULL;
             break;
         }
+        if( ret == 3 && qp >= 0 )
+            pic->i_qpplus1 = qp+1;
     }
 }
 



View it on GitLab: https://code.videolan.org/videolan/x264/-/commit/a8b68ebfaa68621b5ac8907610d3335971839d52

-- 
View it on GitLab: https://code.videolan.org/videolan/x264/-/commit/a8b68ebfaa68621b5ac8907610d3335971839d52
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