From bd026e67a4876cff4e50edfb7f0958c87eacbef0 Mon Sep 17 00:00:00 2001
From: Nicolas George <george@nsup.org>
Date: Sat, 11 Jan 2014 19:42:41 +0100
Subject: [PATCH] lavf: add ffprobe demuxer

With several modifications and documentation by Stefano Sabatini
<stefasab@gmail.com>.

Signed-off-by: Nicolas George <george@nsup.org>
---
 doc/ffprobe-format.texi  | 130 ++++++++++++++++
 libavformat/Makefile     |   1 +
 libavformat/allformats.c |   1 +
 libavformat/ffprobedec.c | 397 +++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 529 insertions(+)
 create mode 100644 doc/ffprobe-format.texi
 create mode 100644 libavformat/ffprobedec.c

diff --git a/doc/ffprobe-format.texi b/doc/ffprobe-format.texi
new file mode 100644
index 0000000..be7af15
--- /dev/null
+++ b/doc/ffprobe-format.texi
@@ -0,0 +1,130 @@
+@chapter ffprobe demuxer format
+@c man begin FFPROBE DEMUXER FORMAT
+
+The ffprobe demuxer format is inspired by the output generated by the
+ffprobe default format.
+
+It consists of several sections (FORMAT, STREAM, PACKET). Each section
+starts with a single line in the format @samp{[SECTION]} and ends with
+the corresponding line @samp{[/SECTION]}.
+
+where @samp{SECTION} is the name of the section.
+
+A well-formed file consists of an initial @samp{FORMAT} section,
+followed by several @samp{STREAM} sections (one per stream), and
+several @samp{PACKET} sections.
+
+Each section contains a sequence of lines in the form
+@sample{key=value}. In the case of data the key and the value must
+stay on different lines.
+
+Unrecognized values are discarded (this allows the demuxer to accept
+the output generated by @program{ffprobe} without further
+modifications.
+
+The following sections document the fields accepted by each section.
+
+@section FORMAT
+
+@table
+@item nb_streams
+the number of supported streams
+@end table
+
+@section STREAM
+@table
+@item index
+the index number
+@item codec_name
+the codec name (the name must be an accepted FFmpeg codec name
+@item time_base
+Specify the time_base as @samp{NUM/DEN}, this is the time base used to
+specify the timestamps in the corresponding packets
+@end table
+
+@section PACKET
+
+@table
+@item stream_index
+the stream index of the stream (must have been specified in a stream
+section). If not specified the first stream is assumed.
+
+@item pts
+the PTS expressed in the corresponding time base stream units
+
+@item pts_time
+the PTS expressed as an absolute time, using the FFmpeg time syntax
+
+@item dts
+the DTS expressed in the corresponding time base stream units
+
+@item pts_time
+the DTS expressed as an absolute time, using the FFmpeg time syntax
+
+@item duration
+the duration expressed in the corresponding time base stream units
+
+@item duration_tim
+the packet duration expressed as an absolute time, using the FFmpeg time syntax
+
+@item flags
+If the value is equal to "K" mark the packet as a key packet
+
+@item data
+specifies the data as a sequence of hexadecimal values (two
+hexadecimal values specify a byte). The data specification starts on
+the following line and can span over several lines, and must be
+terminated by an empty line. Spaces within each line are discarded.
+@end table
+
+@section Examples
+
+A ffprobe demuxer file might look like this:
+@example
+[FORMAT]
+nb_streams=1
+format_name=ffprobe_default
+[/FORMAT]
+[STREAM]
+index=0
+codec_name=timed_id3
+time_base=1/1000000
+[/STREAM]
+[PACKET]
+stream_index=0
+pts_time=0
+dts_time=0
+duration=N/A
+flags=K
+data=
+f000 0000 0167 42c0 1ed9 81b1 fefc 0440
+57ff d7d1 dfff e11a 3d7e 6cbd 0000 0001
+ce8c 4d9d 108e 25e9 fe
+
+[/PACKET]
+[PACKET]
+stream_index=0
+pts_time=1.00
+duration=N/A
+flags=K
+data=
+f000 0000 0141 9a38 3be5 ffff ffff fffa
+ebc1 3782 7d5e 21e9 ffff abf2 ea4f ed66
+0000 0001 ce8c 4d9d 108e 25e9 fe
+
+[/PACKET]
+@end example
+
+The output generated by the @program{ffprobe} default format is valid
+if the following options are also specified:
+@example
+-show_packets -show_data -show_compact_data -show_format -show_streams -show_packets -show_headers_first
+@end example
+
+Thus, to generate the corresponding output from an input file you can
+do:
+@example
+ffprobe INPUT.ts -show_packets -show_data -show_compact_data -show_format -show_streams -show_packets -show_headers_first > OUTPUT.ffprobe
+@end example
+
+@c man end FFPROBE DEMUXER FORMAT
diff --git a/libavformat/Makefile b/libavformat/Makefile
index 5d827d31..04467be 100644
--- a/libavformat/Makefile
+++ b/libavformat/Makefile
@@ -162,6 +162,7 @@ OBJS-$(CONFIG_FFM_DEMUXER)               += ffmdec.o
 OBJS-$(CONFIG_FFM_MUXER)                 += ffmenc.o
 OBJS-$(CONFIG_FFMETADATA_DEMUXER)        += ffmetadec.o
 OBJS-$(CONFIG_FFMETADATA_MUXER)          += ffmetaenc.o
+OBJS-$(CONFIG_FFPROBE_DEFAULT_DEMUXER)   += ffprobedec.o
 OBJS-$(CONFIG_FIFO_MUXER)                += fifo.o
 OBJS-$(CONFIG_FILMSTRIP_DEMUXER)         += filmstripdec.o
 OBJS-$(CONFIG_FILMSTRIP_MUXER)           += filmstripenc.o
diff --git a/libavformat/allformats.c b/libavformat/allformats.c
index 6a216ef..8ef1822 100644
--- a/libavformat/allformats.c
+++ b/libavformat/allformats.c
@@ -123,6 +123,7 @@ void av_register_all(void)
     REGISTER_MUXER   (F4V,              f4v);
     REGISTER_MUXDEMUX(FFM,              ffm);
     REGISTER_MUXDEMUX(FFMETADATA,       ffmetadata);
+    REGISTER_DEMUXER (FFPROBE_DEFAULT,  ffprobe_default);
     REGISTER_MUXER   (FIFO,             fifo);
     REGISTER_MUXDEMUX(FILMSTRIP,        filmstrip);
     REGISTER_MUXDEMUX(FLAC,             flac);
diff --git a/libavformat/ffprobedec.c b/libavformat/ffprobedec.c
new file mode 100644
index 0000000..3a631c9
--- /dev/null
+++ b/libavformat/ffprobedec.c
@@ -0,0 +1,397 @@
+/*
+ * Copyright (c) 2013 Nicolas George
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with FFmpeg; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "libavutil/avassert.h"
+#include "libavutil/avstring.h"
+#include "libavutil/bprint.h"
+#include "libavutil/parseutils.h"
+#include "avformat.h"
+#include "internal.h"
+
+enum SectionType {
+    SEC_NONE = 0,
+    SEC_FORMAT,
+    SEC_STREAM,
+    SEC_PACKET,
+};
+
+const char *const section_names[] = {
+    [SEC_NONE]   = "NONE",
+    [SEC_FORMAT] = "FORMAT",
+    [SEC_STREAM] = "STREAM",
+    [SEC_PACKET] = "PACKET",
+};
+
+typedef struct {
+    AVClass *class;
+    enum SectionType section;
+    AVBPrint data;
+    int packet_nb;
+} FFprobeContext;
+
+static int ffprobe_probe(AVProbeData *probe)
+{
+    unsigned score;
+
+    if (!av_strstart(probe->buf, "[FORMAT]\n", NULL))
+        return 0;
+    score = !!strstr(probe->buf, "\nnb_streams=") +
+            !!strstr(probe->buf, "\nnb_programs=") +
+            !!strstr(probe->buf, "\nformat_name=") +
+            !!strstr(probe->buf, "\nstart_time=") +
+            !!strstr(probe->buf, "\nsize=");
+    return score >= 3 ? AVPROBE_SCORE_MAX : AVPROBE_SCORE_MAX / 2;
+}
+
+static int ffprobe_read_close(AVFormatContext *avf)
+{
+    FFprobeContext *ffp = avf->priv_data;
+
+    av_bprint_finalize(&ffp->data, NULL);
+    return 0;
+}
+
+/**
+ * Read a section start line ("[SECTION]").
+ * Update FFprobeContext.section.
+ * @return  SectionType (>0) for success,
+ *          SEC_NONE if no section start,
+ *          <0 for error
+ */
+static int read_section_start(AVFormatContext *avf)
+{
+    FFprobeContext *ffp = avf->priv_data;
+    uint8_t buf[4096];
+    const char *rest;
+    int i, ret;
+
+    ret = ff_get_line(avf->pb, buf, sizeof(buf));
+    if (ret == 0 && avio_feof(avf->pb))
+        ret = AVERROR_EOF;
+    if (ret <= 0)
+        return ret;
+    if (*buf != '[')
+        return 0;
+    for (i = 1; i < FF_ARRAY_ELEMS(section_names); i++) {
+        if (av_strstart(buf + 1, section_names[i], &rest) &&
+            !strcmp(rest, "]\n")) {
+            ffp->section = i;
+            return i;
+        }
+    }
+    return SEC_NONE;
+}
+
+/**
+ * Read a line from within a section.
+ * @return  >0 for success, 0 if end of section, <0 for error
+ */
+static int read_section_line(AVFormatContext *avf, uint8_t *buf, size_t size)
+{
+    FFprobeContext *ffp = avf->priv_data;
+    const char *rest;
+    int ret;
+    size_t l;
+
+    if ((ret = ff_get_line(avf->pb, buf, size)) <= 0)
+        return ret;
+    if (av_strstart(buf, "[/", &rest)) {
+        ffp->section = 0;
+        return 0;
+    }
+    if ((l = strlen(buf)) > 0 && buf[l - 1] == '\n')
+        buf[--l] = 0;
+    return 1;
+}
+
+/**
+ * Read hexadecimal data
+ * Store it in FFprobeContext.data.
+ * @return  >=0 for success, <0 for error
+ */
+static int read_data(AVFormatContext *avf, int *size)
+{
+    FFprobeContext *ffp = avf->priv_data;
+    uint8_t buf[4096], *cur;
+    int ret, pos, val;
+
+    if (ffp->data.len)
+        return AVERROR_INVALIDDATA;
+    while ((ret = read_section_line(avf, buf, sizeof(buf)))) {
+        if (ret < 0)
+            return ret;
+        if (!buf[0])
+            break;
+        cur = buf;
+        pos = 0;
+        cur += pos;
+        while (1) {
+            while (*cur == ' ')
+                cur++;
+            if (!*cur)
+                break;
+            if ((unsigned)(*cur - '0') >= 10 &&
+                (unsigned)(*cur - 'a') >=  6 &&
+                (unsigned)(*cur - 'A') >=  6) {
+                av_log(avf, AV_LOG_ERROR,
+                       "Invalid character %c in packet number %d data\n", *cur, ffp->packet_nb);
+                return AVERROR_INVALIDDATA;
+            }
+            pos = 0;
+            if (sscanf(cur, " %02x%n", &val, &pos) < 1 || !pos) {
+                av_log(avf, AV_LOG_ERROR,
+                       "Could not parse value in packet number %d data\n", ffp->packet_nb);
+                return AVERROR_INVALIDDATA;
+            }
+            cur += pos;
+            av_bprint_chars(&ffp->data, val, 1);
+        }
+    }
+
+    if (size)
+        *size = ffp->data.len;
+
+    return av_bprint_is_complete(&ffp->data) ? 0 : AVERROR(ENOMEM);
+}
+
+static int read_section_format(AVFormatContext *avf)
+{
+    uint8_t buf[4096];
+    int ret, val;
+
+    while ((ret = read_section_line(avf, buf, sizeof(buf)))) {
+        if (ret < 0)
+            return ret;
+        if (sscanf(buf, "nb_streams=%d", &val) >= 1) {
+            while (avf->nb_streams < val)
+                if (!avformat_new_stream(avf, NULL))
+                    return AVERROR(ENOMEM);
+        }
+        /* TODO programs */
+        /* TODO start_time duration bit_rate */
+        /* TODO tags */
+    }
+    return SEC_FORMAT;
+}
+
+static int read_section_stream(AVFormatContext *avf)
+{
+    FFprobeContext *ffp = avf->priv_data;
+    uint8_t buf[4096];
+    int ret, index, val1, val2;
+    AVStream *st = NULL;
+    const char *val;
+
+    av_bprint_clear(&ffp->data);
+    while ((ret = read_section_line(avf, buf, sizeof(buf)))) {
+        if (ret < 0)
+            return ret;
+        if (!st) {
+            if (sscanf(buf, "index=%d", &index) >= 1) {
+                if (index == avf->nb_streams) {
+                    if (!avformat_new_stream(avf, NULL))
+                        return AVERROR(ENOMEM);
+                }
+                if ((unsigned)index >= avf->nb_streams) {
+                    av_log(avf, AV_LOG_ERROR, "Invalid stream index: %d\n",
+                           index);
+                    return AVERROR_INVALIDDATA;
+                }
+                st = avf->streams[index];
+            } else {
+                av_log(avf, AV_LOG_ERROR, "Stream without index\n");
+                return AVERROR_INVALIDDATA;
+            }
+        }
+        if (av_strstart(buf, "codec_name=", &val)) {
+            const AVCodecDescriptor *desc = avcodec_descriptor_get_by_name(val);
+            if (desc) {
+                st->codecpar->codec_id   = desc->id;
+                st->codecpar->codec_type = desc->type;
+            }
+            if (!desc) {
+                av_log(avf, AV_LOG_WARNING, "Cannot recognize codec name '%s'", val);
+            }
+        } else if (!strcmp(buf, "extradata=")) {
+            if ((ret = read_data(avf, NULL)) < 0)
+                return ret;
+            if (ffp->data.len) {
+                if ((ret = ff_alloc_extradata(st->codecpar, ffp->data.len)) < 0)
+                    return ret;
+                memcpy(st->codecpar->extradata, ffp->data.str, ffp->data.len);
+            }
+        } else if (sscanf(buf, "time_base=%d/%d", &val1, &val2) >= 2) {
+            st->time_base.num = val1;
+            st->time_base.den = val2;
+        }
+    }
+    return SEC_STREAM;
+}
+
+static int read_section_packet(AVFormatContext *avf, AVPacket *pkt)
+{
+    FFprobeContext *ffp = avf->priv_data;
+    uint8_t buf[4096];
+    int ret;
+    AVPacket p;
+    char flags;
+
+    av_init_packet(&p);
+    p.pos = avio_tell(avf->pb);
+    p.stream_index = -1;
+    p.size = -1;
+    av_bprint_clear(&ffp->data);
+    while ((ret = read_section_line(avf, buf, sizeof(buf)))) {
+        int has_time = 0;
+        int64_t pts, dts, duration;
+        char timebuf[1024];
+
+        if (ret < 0)
+            return ret;
+        if (sscanf(buf, "stream_index=%d", &p.stream_index)) {
+            if ((unsigned)p.stream_index >= avf->nb_streams) {
+                av_log(avf, AV_LOG_ERROR, "Invalid stream number %d specified in packet number %d\n",
+                       p.stream_index, ffp->packet_nb);
+                return AVERROR_INVALIDDATA;
+            }
+        }
+
+#define PARSE_TIME(name_, is_duration)                                  \
+        sscanf(buf, #name_ "=%"SCNi64, &p.name_);                       \
+        has_time = sscanf(buf, #name_ "_time=%s", timebuf);             \
+        if (has_time) {                                                 \
+            int stream_index = p.stream_index == -1 ? 0 : p.stream_index; \
+                                                                        \
+            if (!strcmp(timebuf, "N/A")) {                              \
+                p.name_ = is_duration ? 0 : AV_NOPTS_VALUE;             \
+            } else {                                                    \
+                ret = av_parse_time(&name_, timebuf, 1);                \
+                if (ret < 0) {                                          \
+                    av_log(avf, AV_LOG_ERROR, "Invalid " #name_ " time specification '%s' for data packet\n", \
+                           timebuf);                                    \
+                    return ret;                                         \
+                }                                                       \
+                p.name_ = av_rescale_q(name_, AV_TIME_BASE_Q, avf->streams[stream_index]->time_base); \
+            }                                                           \
+        }                                                               \
+
+        PARSE_TIME(pts, 0);
+        PARSE_TIME(dts, 0);
+        PARSE_TIME(duration, 1);
+
+        if (sscanf(buf, "flags=%c", &flags) >= 1)
+            p.flags = flags == 'K' ? AV_PKT_FLAG_KEY : 0;
+        if (!strcmp(buf, "data="))
+            if ((ret = read_data(avf, &p.size)) < 0)
+                return ret;
+    }
+    if (p.size < 0 || (unsigned)p.stream_index >= avf->nb_streams)
+        return SEC_NONE;
+    if ((ret = av_new_packet(pkt, p.size)) < 0)
+        return ret;
+    p.data = pkt->data;
+    p.buf  = pkt->buf;
+    *pkt = p;
+    if (ffp->data.len) {
+        ffp->data.len = FFMIN(ffp->data.len, pkt->size);
+        memcpy(pkt->data, ffp->data.str, ffp->data.len);
+    }
+    return SEC_PACKET;
+}
+
+static int read_section(AVFormatContext *avf, AVPacket *pkt)
+{
+    FFprobeContext *ffp = avf->priv_data;
+    int ret, section;
+
+    while (!ffp->section)
+        if ((ret = read_section_start(avf)) < 0)
+            return ret;
+    switch (section = ffp->section) {
+    case SEC_FORMAT:
+        return read_section_format(avf);
+    case SEC_STREAM:
+        return read_section_stream(avf);
+    case SEC_PACKET:
+        ret = read_section_packet(avf, pkt);
+        ffp->packet_nb++;
+        return ret;
+    default:
+        av_assert0(!"reached");
+        return AVERROR_BUG;
+    }
+}
+
+static int ffprobe_read_header(AVFormatContext *avf)
+{
+    FFprobeContext *ffp = avf->priv_data;
+    int ret;
+
+    av_bprint_init(&ffp->data, 0, AV_BPRINT_SIZE_UNLIMITED);
+    if ((ret = read_section_start(avf)) < 0)
+        return ret;
+    if (ret != SEC_FORMAT) {
+        av_log(avf, AV_LOG_INFO, "Using noheader mode\n");
+        avf->ctx_flags |= AVFMTCTX_NOHEADER;
+        return 0;
+    }
+    if ((ret = read_section_format(avf)) < 0)
+        return ret;
+
+    /* read stream information */
+    while (1) {
+        ret = read_section_start(avf);
+        if (ret != SEC_STREAM)
+            break;
+        if ((ret = read_section_stream(avf)) < 0)
+            return ret;
+    }
+
+    return 0;
+}
+
+static int ffprobe_read_packet(AVFormatContext *avf, AVPacket *pkt)
+{
+    int ret;
+
+    while (1) {
+        if ((ret = read_section(avf, pkt)) < 0)
+            return ret;
+        if (ret == SEC_PACKET)
+            return 0;
+    }
+}
+
+static const AVClass ffprobe_default_class = {
+    .class_name = "ffprobe_default demuxer",
+    .item_name  = av_default_item_name,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
+AVInputFormat ff_ffprobe_default_demuxer = {
+    .name           = "ffprobe_default",
+    .long_name      = NULL_IF_CONFIG_SMALL("FFprobe output (default writer)"),
+    .priv_data_size = sizeof(FFprobeContext),
+    .read_probe     = ffprobe_probe,
+    .read_header    = ffprobe_read_header,
+    .read_packet    = ffprobe_read_packet,
+    .read_close     = ffprobe_read_close,
+    .priv_class     = &ffprobe_default_class,
+};
-- 
1.9.1

