[FFmpeg-devel] [PATCH 2/7 v4] avformat/demux: support inserting bitstream filters in demuxing scenarios

James Almer jamrial at gmail.com
Tue Feb 6 15:05:16 EET 2024


Packets will be passed to the bsf immediately after being generated by a
demuxer, and no further data will be read from the input until all packets
have been returned by the bsf.

Signed-off-by: James Almer <jamrial at gmail.com>
---
No changes since last version

 libavformat/avformat.c |  47 ++++++++++++
 libavformat/demux.c    | 162 ++++++++++++++++++++++++++++++-----------
 libavformat/internal.h |  13 +++-
 libavformat/mux.c      |  43 -----------
 libavformat/mux.h      |  11 ---
 libavformat/rawenc.c   |   1 +
 6 files changed, 181 insertions(+), 96 deletions(-)

diff --git a/libavformat/avformat.c b/libavformat/avformat.c
index 8e8c6fbe55..0e22d47c8b 100644
--- a/libavformat/avformat.c
+++ b/libavformat/avformat.c
@@ -931,3 +931,50 @@ FF_ENABLE_DEPRECATION_WARNINGS
     *pb = NULL;
     return ret;
 }
+
+int ff_stream_add_bitstream_filter(AVStream *st, const char *name, const char *args)
+{
+    int ret;
+    const AVBitStreamFilter *bsf;
+    FFStream *const sti = ffstream(st);
+    AVBSFContext *bsfc;
+
+    av_assert0(!sti->bsfc);
+
+    if (name) {
+        bsf = av_bsf_get_by_name(name);
+        if (!bsf) {
+            av_log(NULL, AV_LOG_ERROR, "Unknown bitstream filter '%s'\n", name);
+            return AVERROR_BSF_NOT_FOUND;
+        }
+        ret = av_bsf_alloc(bsf, &bsfc);
+    } else
+        ret = av_bsf_get_null_filter(&bsfc);
+    if (ret < 0)
+        return ret;
+
+    bsfc->time_base_in = st->time_base;
+    if ((ret = avcodec_parameters_copy(bsfc->par_in, st->codecpar)) < 0) {
+        av_bsf_free(&bsfc);
+        return ret;
+    }
+
+    if (args && bsfc->filter->priv_class) {
+        if ((ret = av_set_options_string(bsfc->priv_data, args, "=", ":")) < 0) {
+            av_bsf_free(&bsfc);
+            return ret;
+        }
+    }
+
+    if ((ret = av_bsf_init(bsfc)) < 0) {
+        av_bsf_free(&bsfc);
+        return ret;
+    }
+
+    sti->bsfc = bsfc;
+
+    av_log(NULL, AV_LOG_VERBOSE,
+           "Automatically inserted bitstream filter '%s'; args='%s'\n",
+           name, args ? args : "");
+    return 1;
+}
diff --git a/libavformat/demux.c b/libavformat/demux.c
index 6f640b92b1..fb9bf9e4ac 100644
--- a/libavformat/demux.c
+++ b/libavformat/demux.c
@@ -540,6 +540,109 @@ static int update_wrap_reference(AVFormatContext *s, AVStream *st, int stream_in
     return 1;
 }
 
+static void update_timestamps(AVFormatContext *s, AVStream *st, AVPacket *pkt)
+{
+    FFStream *const sti = ffstream(st);
+
+    if (update_wrap_reference(s, st, pkt->stream_index, pkt) && sti->pts_wrap_behavior == AV_PTS_WRAP_SUB_OFFSET) {
+        // correct first time stamps to negative values
+        if (!is_relative(sti->first_dts))
+            sti->first_dts = wrap_timestamp(st, sti->first_dts);
+        if (!is_relative(st->start_time))
+            st->start_time = wrap_timestamp(st, st->start_time);
+        if (!is_relative(sti->cur_dts))
+            sti->cur_dts = wrap_timestamp(st, sti->cur_dts);
+    }
+
+    pkt->dts = wrap_timestamp(st, pkt->dts);
+    pkt->pts = wrap_timestamp(st, pkt->pts);
+
+    force_codec_ids(s, st);
+
+    /* TODO: audio: time filter; video: frame reordering (pts != dts) */
+    if (s->use_wallclock_as_timestamps)
+        pkt->dts = pkt->pts = av_rescale_q(av_gettime(), AV_TIME_BASE_Q, st->time_base);
+}
+
+static int filter_packet(AVFormatContext *s, AVStream *st, AVPacket *pkt)
+{
+    FFFormatContext *const si = ffformatcontext(s);
+    FFStream *const sti = ffstream(st);
+    const AVPacket *pkt1;
+    int err;
+
+    if (!sti->bsfc) {
+        const PacketListEntry *pktl = si->raw_packet_buffer.head;
+        if (AVPACKET_IS_EMPTY(pkt))
+            return 0;
+
+        update_timestamps(s, st, pkt);
+
+        if (!pktl && sti->request_probe <= 0)
+            return 0;
+
+        err = avpriv_packet_list_put(&si->raw_packet_buffer, pkt, NULL, 0);
+        if (err < 0) {
+            av_packet_unref(pkt);
+            return err;
+        }
+
+        pkt1 = &si->raw_packet_buffer.tail->pkt;
+        si->raw_packet_buffer_size += pkt1->size;
+
+        if (sti->request_probe <= 0)
+            return 0;
+
+        return probe_codec(s, s->streams[pkt1->stream_index], pkt1);
+    }
+
+    err = av_bsf_send_packet(sti->bsfc, pkt);
+    if (err < 0) {
+        av_log(s, AV_LOG_ERROR,
+                "Failed to send packet to filter %s for stream %d\n",
+                sti->bsfc->filter->name, st->index);
+        return err;
+    }
+
+    do {
+        AVStream *out_st;
+        FFStream *out_sti;
+
+        err = av_bsf_receive_packet(sti->bsfc, pkt);
+        if (err < 0) {
+            if (err == AVERROR(EAGAIN) || err == AVERROR_EOF)
+                return 0;
+            av_log(s, AV_LOG_ERROR, "Error applying bitstream filters to an output "
+                   "packet for stream #%d: %s\n", st->index, av_err2str(err));
+            if (!(s->error_recognition & AV_EF_EXPLODE) && err != AVERROR(ENOMEM))
+                continue;
+            return err;
+        }
+        out_st = s->streams[pkt->stream_index];
+        out_sti = ffstream(out_st);
+
+        update_timestamps(s, out_st, pkt);
+
+        err = avpriv_packet_list_put(&si->raw_packet_buffer, pkt, NULL, 0);
+        if (err < 0) {
+            av_packet_unref(pkt);
+            return err;
+        }
+
+        pkt1 = &si->raw_packet_buffer.tail->pkt;
+        si->raw_packet_buffer_size += pkt1->size;
+
+        if (out_sti->request_probe <= 0)
+            continue;
+
+        err = probe_codec(s, out_st, pkt1);
+        if (err < 0)
+            return err;
+    } while (1);
+
+    return 0;
+}
+
 int ff_read_packet(AVFormatContext *s, AVPacket *pkt)
 {
     FFFormatContext *const si = ffformatcontext(s);
@@ -557,9 +660,6 @@ FF_ENABLE_DEPRECATION_WARNINGS
 
     for (;;) {
         PacketListEntry *pktl = si->raw_packet_buffer.head;
-        AVStream *st;
-        FFStream *sti;
-        const AVPacket *pkt1;
 
         if (pktl) {
             AVStream *const st = s->streams[pktl->pkt.stream_index];
@@ -582,16 +682,27 @@ FF_ENABLE_DEPRECATION_WARNINGS
                We must re-call the demuxer to get the real packet. */
             if (err == FFERROR_REDO)
                 continue;
-            if (!pktl || err == AVERROR(EAGAIN))
+            if (err == AVERROR(EAGAIN))
                 return err;
             for (unsigned i = 0; i < s->nb_streams; i++) {
                 AVStream *const st  = s->streams[i];
                 FFStream *const sti = ffstream(st);
+                int ret;
+
+                // Drain buffered packets in the bsf context on eof
+                if (err == AVERROR_EOF)
+                    if ((ret = filter_packet(s, st, pkt)) < 0)
+                        return ret;
+                pktl = si->raw_packet_buffer.head;
+                if (!pktl)
+                    continue;
                 if (sti->probe_packets || sti->request_probe > 0)
-                    if ((err = probe_codec(s, st, NULL)) < 0)
-                        return err;
+                    if ((ret = probe_codec(s, st, NULL)) < 0)
+                        return ret;
                 av_assert0(sti->request_probe <= 0);
             }
+            if (!pktl)
+                return err;
             continue;
         }
 
@@ -616,42 +727,11 @@ FF_ENABLE_DEPRECATION_WARNINGS
         av_assert0(pkt->stream_index < (unsigned)s->nb_streams &&
                    "Invalid stream index.\n");
 
-        st  = s->streams[pkt->stream_index];
-        sti = ffstream(st);
-
-        if (update_wrap_reference(s, st, pkt->stream_index, pkt) && sti->pts_wrap_behavior == AV_PTS_WRAP_SUB_OFFSET) {
-            // correct first time stamps to negative values
-            if (!is_relative(sti->first_dts))
-                sti->first_dts = wrap_timestamp(st, sti->first_dts);
-            if (!is_relative(st->start_time))
-                st->start_time = wrap_timestamp(st, st->start_time);
-            if (!is_relative(sti->cur_dts))
-                sti->cur_dts = wrap_timestamp(st, sti->cur_dts);
-        }
-
-        pkt->dts = wrap_timestamp(st, pkt->dts);
-        pkt->pts = wrap_timestamp(st, pkt->pts);
-
-        force_codec_ids(s, st);
-
-        /* TODO: audio: time filter; video: frame reordering (pts != dts) */
-        if (s->use_wallclock_as_timestamps)
-            pkt->dts = pkt->pts = av_rescale_q(av_gettime(), AV_TIME_BASE_Q, st->time_base);
-
-        if (!pktl && sti->request_probe <= 0)
-            return 0;
-
-        err = avpriv_packet_list_put(&si->raw_packet_buffer,
-                                     pkt, NULL, 0);
-        if (err < 0) {
-            av_packet_unref(pkt);
-            return err;
-        }
-        pkt1 = &si->raw_packet_buffer.tail->pkt;
-        si->raw_packet_buffer_size += pkt1->size;
-
-        if ((err = probe_codec(s, st, pkt1)) < 0)
+        err = filter_packet(s, s->streams[pkt->stream_index], pkt);
+        if (err < 0)
             return err;
+        if (!AVPACKET_IS_EMPTY(pkt))
+            return 0;
     }
 }
 
diff --git a/libavformat/internal.h b/libavformat/internal.h
index f93832b3c4..c2738a420f 100644
--- a/libavformat/internal.h
+++ b/libavformat/internal.h
@@ -212,7 +212,7 @@ typedef struct FFStream {
     /**
      * bitstream filter to run on stream
      * - encoding: Set by muxer using ff_stream_add_bitstream_filter
-     * - decoding: unused
+     * - decoding: Set by demuxer using ff_stream_add_bitstream_filter
      */
     struct AVBSFContext *bsfc;
 
@@ -752,4 +752,15 @@ int ff_match_url_ext(const char *url, const char *extensions);
 struct FFOutputFormat;
 void avpriv_register_devices(const struct FFOutputFormat * const o[], const AVInputFormat * const i[]);
 
+/**
+ * Add a bitstream filter to a stream.
+ *
+ * @param st output stream to add a filter to
+ * @param name the name of the filter to add
+ * @param args filter-specific argument string
+ * @return  >0 on success;
+ *          AVERROR code on failure
+ */
+int ff_stream_add_bitstream_filter(AVStream *st, const char *name, const char *args);
+
 #endif /* AVFORMAT_INTERNAL_H */
diff --git a/libavformat/mux.c b/libavformat/mux.c
index de10d2c008..4bc8627617 100644
--- a/libavformat/mux.c
+++ b/libavformat/mux.c
@@ -1344,49 +1344,6 @@ int av_get_output_timestamp(struct AVFormatContext *s, int stream,
     return 0;
 }
 
-int ff_stream_add_bitstream_filter(AVStream *st, const char *name, const char *args)
-{
-    int ret;
-    const AVBitStreamFilter *bsf;
-    FFStream *const sti = ffstream(st);
-    AVBSFContext *bsfc;
-
-    av_assert0(!sti->bsfc);
-
-    if (!(bsf = av_bsf_get_by_name(name))) {
-        av_log(NULL, AV_LOG_ERROR, "Unknown bitstream filter '%s'\n", name);
-        return AVERROR_BSF_NOT_FOUND;
-    }
-
-    if ((ret = av_bsf_alloc(bsf, &bsfc)) < 0)
-        return ret;
-
-    bsfc->time_base_in = st->time_base;
-    if ((ret = avcodec_parameters_copy(bsfc->par_in, st->codecpar)) < 0) {
-        av_bsf_free(&bsfc);
-        return ret;
-    }
-
-    if (args && bsfc->filter->priv_class) {
-        if ((ret = av_set_options_string(bsfc->priv_data, args, "=", ":")) < 0) {
-            av_bsf_free(&bsfc);
-            return ret;
-        }
-    }
-
-    if ((ret = av_bsf_init(bsfc)) < 0) {
-        av_bsf_free(&bsfc);
-        return ret;
-    }
-
-    sti->bsfc = bsfc;
-
-    av_log(NULL, AV_LOG_VERBOSE,
-           "Automatically inserted bitstream filter '%s'; args='%s'\n",
-           name, args ? args : "");
-    return 1;
-}
-
 int ff_write_chained(AVFormatContext *dst, int dst_stream, AVPacket *pkt,
                      AVFormatContext *src, int interleave)
 {
diff --git a/libavformat/mux.h b/libavformat/mux.h
index b9ec75641d..ab3e8edd60 100644
--- a/libavformat/mux.h
+++ b/libavformat/mux.h
@@ -171,17 +171,6 @@ const AVPacket *ff_interleaved_peek(AVFormatContext *s, int stream);
 
 int ff_get_muxer_ts_offset(AVFormatContext *s, int stream_index, int64_t *offset);
 
-/**
- * Add a bitstream filter to a stream.
- *
- * @param st output stream to add a filter to
- * @param name the name of the filter to add
- * @param args filter-specific argument string
- * @return  >0 on success;
- *          AVERROR code on failure
- */
-int ff_stream_add_bitstream_filter(AVStream *st, const char *name, const char *args);
-
 /**
  * Write a packet to another muxer than the one the user originally
  * intended. Useful when chaining muxers, where one muxer internally
diff --git a/libavformat/rawenc.c b/libavformat/rawenc.c
index f916db13a2..ec31d76d88 100644
--- a/libavformat/rawenc.c
+++ b/libavformat/rawenc.c
@@ -25,6 +25,7 @@
 #include "libavutil/intreadwrite.h"
 
 #include "avformat.h"
+#include "internal.h"
 #include "rawenc.h"
 #include "mux.h"
 
-- 
2.43.0



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