Commit 9edc0748b6 for ffmpeg
commit 9edc0748b680b1325cc0c1a49e8f1baaba6bb038
Author: Romain Beauxis <romain.beauxis@gmail.com>
Date: Sat Oct 17 12:24:58 2026 +0200
tests/api: add a test of the samples skipped and discarded by decoders
Decode one PCM packet carrying AV_PKT_DATA_SKIP_SAMPLES and print how
many samples are output, for samples skipped at the start of the frame
and padding discarded at its end, alone, together, overlapping, and with
a padding larger than the frame.
The reference records the current behaviour.
diff --git a/tests/api/Makefile b/tests/api/Makefile
index e51dc6c583..7da5f6da32 100644
--- a/tests/api/Makefile
+++ b/tests/api/Makefile
@@ -9,6 +9,7 @@ APITESTPROGS-yes += api-seek api-dump-stream-meta
APITESTPROGS-$(call DEMDEC, H263, H263) += api-band
APITESTPROGS-$(HAVE_THREADS) += api-threadmessage
APITESTPROGS-$(CONFIG_AVCODEC) += api-enc-info
+APITESTPROGS-$(CONFIG_PCM_S16LE_DECODER) += api-skip-samples
APITESTPROGS-$(call ALLYES, H261_ENCODER H261_PARSER) += api-enc-parser
APITESTPROGS += $(APITESTPROGS-yes)
diff --git a/tests/api/api-skip-samples-test.c b/tests/api/api-skip-samples-test.c
new file mode 100644
index 0000000000..7ae2dc8d4f
--- /dev/null
+++ b/tests/api/api-skip-samples-test.c
@@ -0,0 +1,114 @@
+/*
+ * 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
+ */
+
+/**
+ * Decode one packet carrying AV_PKT_DATA_SKIP_SAMPLES and print how many
+ * samples are output, for skips at the start and padding at the end of the
+ * frame, alone, together and overlapping.
+ */
+
+#include <stdio.h>
+#include <string.h>
+
+#include "libavcodec/avcodec.h"
+#include "libavutil/channel_layout.h"
+#include "libavutil/intreadwrite.h"
+#include "libavutil/macros.h"
+
+#define FRAME_SAMPLES 1000
+
+static int decoded_samples(uint32_t skip, uint32_t discard)
+{
+ const AVCodec *codec = avcodec_find_decoder(AV_CODEC_ID_PCM_S16LE);
+ AVCodecContext *ctx = NULL;
+ AVPacket *pkt = NULL;
+ AVFrame *frame = NULL;
+ uint8_t *side;
+ int nb_samples = 0;
+ int ret;
+
+ ctx = avcodec_alloc_context3(codec);
+ pkt = av_packet_alloc();
+ frame = av_frame_alloc();
+ if (!ctx || !pkt || !frame) {
+ ret = AVERROR(ENOMEM);
+ goto end;
+ }
+
+ ctx->sample_rate = 48000;
+ ctx->pkt_timebase = (AVRational){ 1, 48000 };
+ av_channel_layout_default(&ctx->ch_layout, 1);
+ ret = avcodec_open2(ctx, codec, NULL);
+ if (ret < 0)
+ goto end;
+
+ ret = av_new_packet(pkt, FRAME_SAMPLES * 2);
+ if (ret < 0)
+ goto end;
+ memset(pkt->data, 0, pkt->size);
+ pkt->pts = 0;
+ side = av_packet_new_side_data(pkt, AV_PKT_DATA_SKIP_SAMPLES, 10);
+ if (!side) {
+ ret = AVERROR(ENOMEM);
+ goto end;
+ }
+ AV_WL32(side, skip);
+ AV_WL32(side + 4, discard);
+
+ ret = avcodec_send_packet(ctx, pkt);
+ if (ret < 0)
+ goto end;
+ ret = avcodec_send_packet(ctx, NULL);
+ if (ret < 0)
+ goto end;
+ while ((ret = avcodec_receive_frame(ctx, frame)) >= 0) {
+ nb_samples += frame->nb_samples;
+ av_frame_unref(frame);
+ }
+ ret = ret == AVERROR_EOF ? nb_samples : ret;
+
+end:
+ av_frame_free(&frame);
+ av_packet_free(&pkt);
+ avcodec_free_context(&ctx);
+ return ret;
+}
+
+int main(void)
+{
+ static const uint32_t cases[][2] = {
+ { 0, 0 },
+ { 300, 0 },
+ { 0, 400 },
+ { 300, 400 },
+ { 300, 700 },
+ { 300, 800 },
+ { 300, 1100 },
+ };
+
+ for (int i = 0; i < FF_ARRAY_ELEMS(cases); i++) {
+ int ret = decoded_samples(cases[i][0], cases[i][1]);
+ if (ret < 0) {
+ fprintf(stderr, "decoding failed: %s\n", av_err2str(ret));
+ return 1;
+ }
+ printf("frame %d skip %4"PRIu32" discard %4"PRIu32": %d samples\n",
+ FRAME_SAMPLES, cases[i][0], cases[i][1], ret);
+ }
+ return 0;
+}
diff --git a/tests/fate/api.mak b/tests/fate/api.mak
index ca836a40e3..7b90e3dd3b 100644
--- a/tests/fate/api.mak
+++ b/tests/fate/api.mak
@@ -7,6 +7,10 @@ fate-api-flac: $(APITESTSDIR)/api-flac-test$(EXESUF)
fate-api-flac: CMD = run $(APITESTSDIR)/api-flac-test$(EXESUF)
fate-api-flac: CMP = null
+FATE_API_LIBAVCODEC-$(CONFIG_PCM_S16LE_DECODER) += fate-api-skip-samples
+fate-api-skip-samples: $(APITESTSDIR)/api-skip-samples-test$(EXESUF)
+fate-api-skip-samples: CMD = run $(APITESTSDIR)/api-skip-samples-test$(EXESUF)
+
FATE_API_LIBAVCODEC-$(CONFIG_MOVTEXT_ENCODER) += fate-api-movtext
fate-api-movtext: $(APITESTSDIR)/api-movtext-test$(EXESUF)
fate-api-movtext: CMD = run $(APITESTSDIR)/api-movtext-test$(EXESUF)
diff --git a/tests/ref/fate/api-skip-samples b/tests/ref/fate/api-skip-samples
new file mode 100644
index 0000000000..b182d5dcdf
--- /dev/null
+++ b/tests/ref/fate/api-skip-samples
@@ -0,0 +1,7 @@
+frame 1000 skip 0 discard 0: 1000 samples
+frame 1000 skip 300 discard 0: 700 samples
+frame 1000 skip 0 discard 400: 600 samples
+frame 1000 skip 300 discard 400: 300 samples
+frame 1000 skip 300 discard 700: 0 samples
+frame 1000 skip 300 discard 800: 700 samples
+frame 1000 skip 300 discard 1100: 700 samples