[FFmpeg-devel] [PATCH] fftools/ffmpeg_opt: Add -toeof option to stop reading at position relative to EOF

[morten.with at gmail.com]

From: withmorten <morten.with at gmail.com>

Fixes ticket #7155: Add option to stop writing at position relative to EOF

Signed-off-by: Morten With <morten.with at gmail.com>
---
 doc/ffmpeg.texi      |  6 ++++++
 fftools/ffmpeg.h     |  1 +
 fftools/ffmpeg_opt.c | 31 +++++++++++++++++++++++++++++++
 3 files changed, 38 insertions(+)

diff --git a/doc/ffmpeg.texi b/doc/ffmpeg.texi
index 3717f22d42..f627f0e8a5 100644
--- a/doc/ffmpeg.texi
+++ b/doc/ffmpeg.texi
@@ -488,6 +488,12 @@ see @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1)
 
 -to and -t are mutually exclusive and -t has priority.
 
+ at item -toeof @var{position} (@emph{input})
+Stop reading the input at @var{position} relative to the "end of file". That is,
+larger negative values are later in the file, 0 is at EOF.
+
+-toeof and -to, as well as -toeof and -t, are mutually exclusive, and -to, or respectively -t, has priority.
+
 @item -fs @var{limit_size} (@emph{output})
 Set the file size limit, expressed in bytes. No further chunk of bytes is written
 after the limit is exceeded. The size of the output file is slightly more than the
diff --git a/fftools/ffmpeg.h b/fftools/ffmpeg.h
index eb1eaf6363..70026b376e 100644
--- a/fftools/ffmpeg.h
+++ b/fftools/ffmpeg.h
@@ -149,6 +149,7 @@ typedef struct OptionsContext {
 
     int64_t recording_time;
     int64_t stop_time;
+    int64_t stop_time_eof;
     uint64_t limit_filesize;
     float mux_preload;
     float mux_max_delay;
diff --git a/fftools/ffmpeg_opt.c b/fftools/ffmpeg_opt.c
index 58ec13e5a8..30fd28ec3a 100644
--- a/fftools/ffmpeg_opt.c
+++ b/fftools/ffmpeg_opt.c
@@ -159,6 +159,7 @@ static void init_options(OptionsContext *o)
     memset(o, 0, sizeof(*o));
 
     o->stop_time = INT64_MAX;
+    o->stop_time_eof  = AV_NOPTS_VALUE;
     o->mux_max_delay  = 0.7;
     o->start_time     = AV_NOPTS_VALUE;
     o->start_time_eof = AV_NOPTS_VALUE;
@@ -979,6 +980,16 @@ static int open_input_file(OptionsContext *o, const char *filename)
         av_log(NULL, AV_LOG_WARNING, "-t and -to cannot be used together; using -t.\n");
     }
 
+    if (o->stop_time_eof != AV_NOPTS_VALUE && o->recording_time != INT64_MAX) {
+        o->stop_time_eof = AV_NOPTS_VALUE;
+        av_log(NULL, AV_LOG_WARNING, "-t and -toeof cannot be used together; using -t for %s.\n", filename);
+    }
+
+    if (o->stop_time != INT64_MAX && o->stop_time_eof != AV_NOPTS_VALUE) {
+        o->stop_time_eof = AV_NOPTS_VALUE;
+        av_log(NULL, AV_LOG_WARNING, "-to and -toeof cannot be used together; using -to for %s.\n", filename);
+    }
+
     if (o->stop_time != INT64_MAX && o->recording_time == INT64_MAX) {
         int64_t start_time = o->start_time == AV_NOPTS_VALUE ? 0 : o->start_time;
         if (o->stop_time <= start_time) {
@@ -1122,6 +1133,24 @@ static int open_input_file(OptionsContext *o, const char *filename)
         } else
             av_log(NULL, AV_LOG_WARNING, "Cannot use -sseof, duration of %s not known\n", filename);
     }
+
+    if (o->stop_time_eof != AV_NOPTS_VALUE) {
+        if (o->stop_time_eof >= 0) {
+            av_log(NULL, AV_LOG_ERROR, "-toeof value must be negative; aborting\n");
+            exit_program(1);
+        }
+        if (ic->duration > 0) {
+            o->recording_time = ic->duration + o->stop_time_eof;
+            if (o->start_time != AV_NOPTS_VALUE) {
+                o->recording_time -= o->start_time;
+                if (o->recording_time <= 0) {
+                    av_log(NULL, AV_LOG_WARNING, "-toeof value seeks to before start of file %s; ignored\n", filename);
+                    o->recording_time += o->start_time;
+                }
+            }
+        } else
+            av_log(NULL, AV_LOG_WARNING, "Cannot use -toeof, duration of %s not known\n", filename);
+    }
     timestamp = (o->start_time == AV_NOPTS_VALUE) ? 0 : o->start_time;
     /* add the stream start time */
     if (!o->seek_timestamp && ic->start_time != AV_NOPTS_VALUE)
@@ -3347,6 +3376,8 @@ const OptionDef options[] = {
         "duration" },
     { "to",             HAS_ARG | OPT_TIME | OPT_OFFSET | OPT_INPUT | OPT_OUTPUT,  { .off = OFFSET(stop_time) },
         "record or transcode stop time", "time_stop" },
+    { "toeof",          HAS_ARG | OPT_TIME | OPT_OFFSET | OPT_INPUT, { .off = OFFSET(stop_time_eof) },
+        "input stop time relative to EOF", "time_stop" },
     { "fs",             HAS_ARG | OPT_INT64 | OPT_OFFSET | OPT_OUTPUT, { .off = OFFSET(limit_filesize) },
         "set the limit file size in bytes", "limit_size" },
     { "ss",             HAS_ARG | OPT_TIME | OPT_OFFSET |
-- 
2.17.1