Insert (a)trim filters on the corresponding inputs, so the extra frames
are decoded and discarded.
---
Changelog | 2 ++
avconv.h | 1 +
avconv_filter.c | 54 +++++++++++++++++++++++++++++++++++++++---------------
avconv_opt.c | 1 +
doc/avconv.texi | 10 +++++++---
5 files changed, 50 insertions(+), 18 deletions(-)
diff --git a/Changelog b/Changelog
index 7a2a7c8..b6744d5 100644
--- a/Changelog
+++ b/Changelog
@@ -25,6 +25,8 @@ version 10:
- support for WavPack muxing (raw and in Matroska)
- Go2Webinar decoder
- WavPack encoding through libwavpack
+- when transcoding with avconv (i.e. not streamcopying), -ss is now accurate
+ even when used as an input option
version 9:
diff --git a/avconv.h b/avconv.h
index 1244d86..ad59bcd 100644
--- a/avconv.h
+++ b/avconv.h
@@ -237,6 +237,7 @@ typedef struct InputFile {
int eagain; /* true if last read attempt returned EAGAIN */
int ist_index; /* index of first stream in ist_table */
int64_t ts_offset;
+ int64_t start_time; /* user-specified start time in AV_TIME_BASE or
AV_NOPTS_VALUE */
int nb_streams; /* number of stream that avconv is aware of; may be
different
from ctx.nb_streams if new streams appear during
av_read_frame() */
int rate_emu;
diff --git a/avconv_filter.c b/avconv_filter.c
index b9abde8..81ec474 100644
--- a/avconv_filter.c
+++ b/avconv_filter.c
@@ -173,17 +173,18 @@ static void init_input_filter(FilterGraph *fg,
AVFilterInOut *in)
ist->filters[ist->nb_filters - 1] = fg->inputs[fg->nb_inputs - 1];
}
-static int insert_trim(OutputStream *ost, AVFilterContext **last_filter, int
*pad_idx)
+static int insert_trim(int64_t start_time, int64_t duration,
+ AVFilterContext **last_filter, int *pad_idx,
+ const char *filter_name)
{
- OutputFile *of = output_files[ost->file_index];
AVFilterGraph *graph = (*last_filter)->graph;
AVFilterContext *ctx;
const AVFilter *trim;
- const char *name = ost->st->codec->codec_type == AVMEDIA_TYPE_VIDEO ?
"trim" : "atrim";
- char filter_name[128];
+ enum AVMediaType type = avfilter_pad_get_type((*last_filter)->output_pads,
*pad_idx);
+ const char *name = (type == AVMEDIA_TYPE_VIDEO) ? "trim" : "atrim";
int ret = 0;
- if (of->recording_time == INT64_MAX && of->start_time == AV_NOPTS_VALUE)
+ if (duration == INT64_MAX && start_time == AV_NOPTS_VALUE)
return 0;
trim = avfilter_get_by_name(name);
@@ -193,18 +194,16 @@ static int insert_trim(OutputStream *ost, AVFilterContext
**last_filter, int *pa
return AVERROR_FILTER_NOT_FOUND;
}
- snprintf(filter_name, sizeof(filter_name), "%s for output stream %d:%d",
- name, ost->file_index, ost->index);
ctx = avfilter_graph_alloc_filter(graph, trim, filter_name);
if (!ctx)
return AVERROR(ENOMEM);
- if (of->recording_time != INT64_MAX) {
- ret = av_opt_set_double(ctx, "duration", (double)of->recording_time /
1e6,
+ if (duration != INT64_MAX) {
+ ret = av_opt_set_double(ctx, "duration", (double)duration / 1e6,
AV_OPT_SEARCH_CHILDREN);
}
- if (ret >= 0 && of->start_time != AV_NOPTS_VALUE) {
- ret = av_opt_set_double(ctx, "start", (double)of->start_time / 1e6,
+ if (ret >= 0 && start_time != AV_NOPTS_VALUE) {
+ ret = av_opt_set_double(ctx, "start", (double)start_time / 1e6,
AV_OPT_SEARCH_CHILDREN);
}
if (ret < 0) {
@@ -229,6 +228,7 @@ static int configure_output_video_filter(FilterGraph *fg,
OutputFilter *ofilter,
{
char *pix_fmts;
OutputStream *ost = ofilter->ost;
+ OutputFile *of = output_files[ost->file_index];
AVCodecContext *codec = ost->st->codec;
AVFilterContext *last_filter = out->filter_ctx;
int pad_idx = out->pad_idx;
@@ -299,7 +299,10 @@ static int configure_output_video_filter(FilterGraph *fg,
OutputFilter *ofilter,
pad_idx = 0;
}
- ret = insert_trim(ost, &last_filter, &pad_idx);
+ snprintf(name, sizeof(name), "trim for output stream %d:%d",
+ ost->file_index, ost->index);
+ ret = insert_trim(of->start_time, of->recording_time,
+ &last_filter, &pad_idx, name);
if (ret < 0)
return ret;
@@ -313,6 +316,7 @@ static int configure_output_video_filter(FilterGraph *fg,
OutputFilter *ofilter,
static int configure_output_audio_filter(FilterGraph *fg, OutputFilter
*ofilter, AVFilterInOut *out)
{
OutputStream *ost = ofilter->ost;
+ OutputFile *of = output_files[ost->file_index];
AVCodecContext *codec = ost->st->codec;
AVFilterContext *last_filter = out->filter_ctx;
int pad_idx = out->pad_idx;
@@ -370,7 +374,10 @@ static int configure_output_audio_filter(FilterGraph *fg,
OutputFilter *ofilter,
pad_idx = 0;
}
- ret = insert_trim(ost, &last_filter, &pad_idx);
+ snprintf(name, sizeof(name), "trim for output stream %d:%d",
+ ost->file_index, ost->index);
+ ret = insert_trim(of->start_time, of->recording_time,
+ &last_filter, &pad_idx, name);
if (ret < 0)
return ret;
@@ -415,11 +422,12 @@ static int configure_input_video_filter(FilterGraph *fg,
InputFilter *ifilter,
AVFilterContext *last_filter;
const AVFilter *buffer = avfilter_get_by_name("buffer");
InputStream *ist = ifilter->ist;
+ InputFile *f = input_files[ist->file_index];
AVRational tb = ist->framerate.num ? av_inv_q(ist->framerate) :
ist->st->time_base;
AVRational sar;
char args[255], name[255];
- int ret;
+ int ret, pad_idx = 0;
sar = ist->st->sample_aspect_ratio.num ?
ist->st->sample_aspect_ratio :
@@ -452,6 +460,13 @@ static int configure_input_video_filter(FilterGraph *fg,
InputFilter *ifilter,
last_filter = setpts;
}
+ snprintf(name, sizeof(name), "trim for input stream %d:%d",
+ ist->file_index, ist->st->index);
+ ret = insert_trim((f->start_time == AV_NOPTS_VALUE) ? AV_NOPTS_VALUE : 0,
INT64_MAX,
+ &last_filter, &pad_idx, name);
+ if (ret < 0)
+ return ret;
+
if ((ret = avfilter_link(last_filter, 0, in->filter_ctx, in->pad_idx)) < 0)
return ret;
return 0;
@@ -463,8 +478,9 @@ static int configure_input_audio_filter(FilterGraph *fg,
InputFilter *ifilter,
AVFilterContext *last_filter;
const AVFilter *abuffer = avfilter_get_by_name("abuffer");
InputStream *ist = ifilter->ist;
+ InputFile *f = input_files[ist->file_index];
char args[255], name[255];
- int ret;
+ int ret, pad_idx = 0;
snprintf(args, sizeof(args), "time_base=%d/%d:sample_rate=%d:sample_fmt=%s"
":channel_layout=0x%"PRIx64,
@@ -530,6 +546,14 @@ static int configure_input_audio_filter(FilterGraph *fg,
InputFilter *ifilter,
last_filter = volume;
}
+
+ snprintf(name, sizeof(name), "trim for input stream %d:%d",
+ ist->file_index, ist->st->index);
+ ret = insert_trim((f->start_time == AV_NOPTS_VALUE) ? AV_NOPTS_VALUE : 0,
INT64_MAX,
+ &last_filter, &pad_idx, name);
+ if (ret < 0)
+ return ret;
+
if ((ret = avfilter_link(last_filter, 0, in->filter_ctx, in->pad_idx)) < 0)
return ret;
diff --git a/avconv_opt.c b/avconv_opt.c
index fbaac86..d856985 100644
--- a/avconv_opt.c
+++ b/avconv_opt.c
@@ -681,6 +681,7 @@ static int open_input_file(OptionsContext *o, const char
*filename)
f->ctx = ic;
f->ist_index = nb_input_streams - ic->nb_streams;
+ f->start_time = o->start_time;
f->ts_offset = o->input_ts_offset - (copy_ts ? 0 : timestamp);
f->nb_streams = ic->nb_streams;
f->rate_emu = o->rate_emu;
diff --git a/doc/avconv.texi b/doc/avconv.texi
index 1842422..517700a 100644
--- a/doc/avconv.texi
+++ b/doc/avconv.texi
@@ -262,9 +262,13 @@ Set the file size limit.
@item -ss @var{position} (@emph{input/output})
When used as an input option (before @code{-i}), seeks in this input file to
-@var{position}. When used as an output option (before an output filename),
-decodes but discards input until the timestamps reach @var{position}. This is
-slower, but more accurate.
+@var{position}. Note the in most formats it is not possible to seek exactly, so
+@command{avconv} will seek to the closest seek point before @var{position}.
+When transcoding, this extra segment between the seek point and @var{position}
+will be decoded and discarded. When doing stream copy, it will be preserved.
+
+When used as an output option (before an output filename), decodes but discards
+input until the timestamps reach @var{position}.
@var{position} may be either in seconds or in @code{hh:mm:ss[.xxx]} form.
--
1.7.10.4
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