Work on function for transcoding of audio stream

setup/extensions.json

@@ -19,7 +19,7 @@
     {
         "name": "ffmpeg",
         "sources": "calibre/utils/ffmpeg.c",
-		"libraries": "swresample avcodec avutil",
+		"libraries": "swresample avcodec avformat avutil",
         "inc_dirs": "!ffmpeg_inc_dirs",
         "lib_dirs": "!ffmpeg_lib_dirs",
 		"needs_c": "99"

src/calibre/utils/ffmpeg.c

@@ -26,12 +26,354 @@
 
 static PyObject*
 averror_as_python(int errnum, int line) {
-    char avbuf[4096];
+    if (!PyErr_Occurred()) {  // python error happened in a callback function for example
-    av_strerror(errnum, avbuf, sizeof(avbuf));
+        char avbuf[4096];
-    PyErr_Format(PyExc_Exception, "%s:%d:%s", __FILE__, line, avbuf);
+        av_strerror(errnum, avbuf, sizeof(avbuf));
+        PyErr_Format(PyExc_Exception, "%s:%d:%s", __FILE__, line, avbuf);
+    }
     return NULL;
 }
 
+typedef struct Transcoder {
+    AVCodecContext *dec_ctx, *enc_ctx;
+    AVFrame *dec_frame;
+    AVFormatContext *ifmt_ctx, *ofmt_ctx;
+    AVIOContext *input_ctx, *output_ctx;
+    AVPacket *pkt;
+    PyObject *write_output, *read_input, *seek_in_input, *seek_in_output;
+    unsigned int output_bitrate;
+    const char *container_format, *output_codec_name;
+    AVAudioFifo *fifo;
+    SwrContext *resample_ctx;
+    int64_t pts;
+} Transcoder;
+
+#define check_call(func, ...) if ((ret = func(__VA_ARGS__)) < 0) return averror_as_python(ret, __LINE__);
+
+static int
+read_packet(void *opaque, uint8_t *buf, int buf_size) {
+    PyObject *psz = PyLong_FromLong((long)buf_size);
+    PyObject *ret = PyObject_CallOneArg(((Transcoder*)opaque)->read_input, psz);
+    Py_DECREF(psz);
+    if (!ret) return AVERROR_EXTERNAL;
+    Py_buffer b;
+    if (PyObject_GetBuffer(ret, &b, PyBUF_SIMPLE) != 0) return AVERROR_EXTERNAL;
+    memcpy(buf, b.buf, b.len < buf_size ? b.len : buf_size);
+    Py_DECREF(ret); PyBuffer_Release(&b);
+    return b.len;
+}
+
+
+static int
+write_packet(void *opaque, const uint8_t *buf, int buf_size) {
+    Transcoder *t = opaque;
+    PyObject *mv = PyMemoryView_FromMemory((char*)buf, buf_size, PyBUF_READ);
+    if (!mv) return AVERROR_EXTERNAL;
+    PyObject *ret = PyObject_CallOneArg(t->write_output, mv);
+    Py_DECREF(mv);
+    if (!ret) return AVERROR_EXTERNAL;
+    int ans = PyLong_AsLong(ret);
+    Py_DECREF(ret);
+    return ans;
+}
+
+static int64_t
+seek_packet(PyObject *seek_func, int64_t offset, int whence) {
+    PyObject *ret = PyObject_CallFunction(seek_func, "Li", offset, whence);
+    if (!ret) return AVERROR_EXTERNAL;
+    long long ans = PyLong_AsLongLong(ret);
+    Py_DECREF(ret);
+    return ans;
+}
+
+static int64_t
+seek_packet_input(void *opaque, int64_t offset, int whence) { return seek_packet(((Transcoder*)opaque)->seek_in_input, offset, whence); }
+
+static int64_t
+seek_packet_output(void *opaque, int64_t offset, int whence) { return seek_packet(((Transcoder*)opaque)->seek_in_output, offset, whence); }
+
+static PyObject*
+open_input_file(Transcoder *t) {
+    if (!(t->ifmt_ctx = avformat_alloc_context())) { PyErr_NoMemory(); return NULL; }
+    static const size_t io_bufsize = 8192;
+    uint8_t *input_buf;
+    if (!(input_buf = av_malloc(io_bufsize))) { PyErr_NoMemory(); return NULL; }
+    if (!(t->input_ctx =  avio_alloc_context(input_buf, io_bufsize, 0, t, &read_packet, NULL, &seek_packet_input))) { PyErr_NoMemory(); return NULL; }
+    t->ifmt_ctx->pb = t->input_ctx;
+    int ret;
+    check_call(avformat_open_input, &t->ifmt_ctx, NULL, NULL, NULL);
+    check_call(avformat_find_stream_info, t->ifmt_ctx, NULL);
+    if (t->ifmt_ctx->nb_streams != 1) {
+        PyErr_Format(PyExc_ValueError, "input file must have only one stream, it has: %u streams", t->ifmt_ctx->nb_streams); return NULL;
+    }
+    const AVStream *stream = t->ifmt_ctx->streams[0];
+    const AVCodec *input_codec = avcodec_find_decoder(stream->codecpar->codec_id);
+    if (!input_codec) {
+        PyErr_SetString(PyExc_ValueError, "could not find codec to decode input file"); return NULL;
+    }
+    if (!(t->dec_ctx = avcodec_alloc_context3(input_codec))) return PyErr_NoMemory();
+    check_call(avcodec_parameters_to_context, t->dec_ctx, stream->codecpar);
+    check_call(avcodec_open2, t->dec_ctx, input_codec, NULL);
+    t->dec_ctx->pkt_timebase = stream->time_base;
+    return Py_True;
+}
+
+static PyObject*
+open_output_file(Transcoder *t) {
+    if (!(t->ofmt_ctx = avformat_alloc_context())) { PyErr_NoMemory(); return NULL; }
+    static const size_t io_bufsize = 8192;
+    uint8_t *input_buf;
+    if (!(input_buf = av_malloc(io_bufsize))) { PyErr_NoMemory(); return NULL; }
+    if (!(t->output_ctx = avio_alloc_context(input_buf, io_bufsize, 0, t, NULL, &write_packet, &seek_packet_output))) { PyErr_NoMemory(); return NULL; }
+    t->ofmt_ctx->pb = t->output_ctx;
+
+    if (!(t->ofmt_ctx->oformat = av_guess_format(t->container_format, NULL, NULL))) {
+        PyErr_Format(PyExc_KeyError, "unknown output container format: %s", t->container_format); return NULL;
+    }
+    const AVCodec *output_codec = NULL;
+    if (!t->output_codec_name[0]) {
+        if (!(output_codec = avcodec_find_encoder(t->ofmt_ctx->oformat->audio_codec))) {
+            PyErr_Format(PyExc_RuntimeError, "Default audio output codec for %s not available", t->ofmt_ctx->oformat->long_name); return NULL;
+        }
+    } else {
+        if (!(output_codec = avcodec_find_encoder_by_name(t->output_codec_name))) {
+            PyErr_Format(PyExc_KeyError, "unknown output codec: %s", t->output_codec_name); return NULL;
+        }
+    }
+    AVStream *stream = NULL;
+    if (!(stream = avformat_new_stream(t->ofmt_ctx, NULL))) return PyErr_NoMemory();
+    if (!(t->enc_ctx = avcodec_alloc_context3(output_codec))) return PyErr_NoMemory();
+
+    // Setup encoding parameters
+    av_channel_layout_default(&t->enc_ctx->ch_layout, t->dec_ctx->ch_layout.nb_channels);
+    t->enc_ctx->sample_rate = t->dec_ctx->sample_rate;
+    t->enc_ctx->sample_fmt = output_codec->sample_fmts[0];
+    t->enc_ctx->bit_rate = t->output_bitrate;
+    if (!t->enc_ctx->bit_rate) {
+        switch (output_codec->id) {
+            case AV_CODEC_ID_AAC: t->enc_ctx->bit_rate = 96; break;
+            case AV_CODEC_ID_MP3: t->enc_ctx->bit_rate = 192; break;
+            default: t->enc_ctx->bit_rate = 128;
+        }
+        t->enc_ctx->bit_rate *= 1000 * t->enc_ctx->ch_layout.nb_channels;
+    }
+    stream->time_base.den = t->dec_ctx->sample_rate;
+    stream->time_base.num = 1;
+    if (t->ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER) t->enc_ctx->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
+    int ret;
+    check_call(avcodec_open2, t->enc_ctx, output_codec, NULL);
+    check_call(avcodec_parameters_from_context, stream->codecpar, t->enc_ctx);
+    return Py_True;
+}
+
+static PyObject*
+add_samples_to_fifo(AVAudioFifo *fifo, uint8_t **converted_input_samples, const int frame_size) {
+    int ret;
+
+    /* Make the FIFO as large as it needs to be to hold both,
+     * the old and the new samples. */
+    check_call(av_audio_fifo_realloc, fifo, av_audio_fifo_size(fifo) + frame_size);
+    /* Store the new samples in the FIFO buffer. */
+    if (av_audio_fifo_write(fifo, (void **)converted_input_samples, frame_size) < frame_size) {
+        PyErr_SetString(PyExc_Exception, "could not write data to FIFO"); return NULL;
+    }
+    return Py_True;
+}
+
+static PyObject*
+decode_audio_frame(AVFrame *input_frame, AVFormatContext *input_format_context, AVCodecContext *input_codec_context, bool *data_present, bool *finished) {
+    AVPacket *input_packet = av_packet_alloc();
+    if (!input_packet) return PyErr_NoMemory();
+    *data_present = false;
+    *finished = false;
+    int ret;
+    PyObject *r = NULL;
+    if ((ret = av_read_frame(input_format_context, input_packet)) < 0) {
+        if (ret == AVERROR_EOF) *finished = 1;
+        else { averror_as_python(ret, __LINE__); goto cleanup; }
+    }
+    Py_BEGIN_ALLOW_THREADS;
+    ret = avcodec_send_packet(input_codec_context, input_packet);
+    Py_END_ALLOW_THREADS;
+    if (ret < 0) { averror_as_python(ret, __LINE__); goto cleanup; }
+    Py_BEGIN_ALLOW_THREADS;
+    ret = avcodec_receive_frame(input_codec_context, input_frame);
+    Py_END_ALLOW_THREADS;
+    if (ret == AVERROR(EAGAIN)) { r = Py_True; goto cleanup; }
+    if (ret == AVERROR_EOF) { r = Py_True; *finished = true; goto cleanup; }
+    if (ret < 0) { averror_as_python(ret, __LINE__); goto cleanup; }
+    *data_present = true;
+cleanup:
+    av_packet_free(&input_packet);
+    return r;
+}
+
+static PyObject*
+read_decode_convert_and_store(Transcoder *t, bool *finished) {
+    PyObject *r = NULL;
+    int ret;
+    AVFrame *input_frame = av_frame_alloc();
+    uint8_t **converted_input_samples = NULL;
+    if (!input_frame) { PyErr_NoMemory(); goto cleanup; }
+    bool data_present = false;
+    if (!decode_audio_frame(input_frame, t->ifmt_ctx, t->dec_ctx, &data_present, finished)) goto cleanup;
+    if (*finished) { r = Py_True; goto cleanup; }
+    if (data_present) {
+        // Convert the samples to the format needed by the encoder
+        if ((ret = av_samples_alloc_array_and_samples(
+                &converted_input_samples, NULL, t->enc_ctx->ch_layout.nb_channels,
+                input_frame->nb_samples, t->enc_ctx->sample_fmt, 0)) < 0) { averror_as_python(ret, __LINE__); goto cleanup; }
+        Py_BEGIN_ALLOW_THREADS;
+        ret = swr_convert(t->resample_ctx, converted_input_samples, input_frame->nb_samples, (const uint8_t**)input_frame->extended_data, input_frame->nb_samples);
+        Py_END_ALLOW_THREADS;
+        if (ret < 0) { averror_as_python(ret, __LINE__); goto cleanup; }
+        // Add the converted input samples to the FIFO buffer for later processing.
+        if (!add_samples_to_fifo(t->fifo, converted_input_samples, input_frame->nb_samples)) goto cleanup;
+    }
+
+    r = Py_True;
+cleanup:
+    if (converted_input_samples) av_freep(&converted_input_samples[0]);
+    av_freep(&converted_input_samples);
+    av_frame_free(&input_frame);
+    return r;
+}
+
+
+static PyObject*
+encode_audio_frame(AVFrame *frame, AVFormatContext *output_format_context, AVCodecContext *output_codec_context, bool *data_present, int64_t *pts) {
+    AVPacket *output_packet = av_packet_alloc();
+    if (!output_packet) return PyErr_NoMemory();
+
+    if (frame) {
+        frame->pts = *pts;
+        *pts += frame->nb_samples;
+    }
+    *data_present = false;
+    int ret;
+    PyObject *r = NULL;
+    Py_BEGIN_ALLOW_THREADS;
+    ret = avcodec_send_frame(output_codec_context, frame);
+    Py_END_ALLOW_THREADS;
+    if (ret < 0 && ret != AVERROR_EOF) {
+        averror_as_python(ret, __LINE__); goto cleanup;
+    }
+    Py_BEGIN_ALLOW_THREADS;
+    ret = avcodec_receive_packet(output_codec_context, output_packet);
+    Py_END_ALLOW_THREADS;
+    if (ret == AVERROR(EAGAIN)) {
+        goto ok;
+        /* If the last frame has been encoded, stop encoding. */
+    } else if (ret == AVERROR_EOF) {
+        goto ok;
+    } else if (ret < 0) {
+        averror_as_python(ret, __LINE__);
+        goto cleanup;
+        /* Default case: Return encoded data. */
+    } else {
+        *data_present = true;
+    }
+    if (*data_present && (ret = av_write_frame(output_format_context, output_packet)) < 0) {
+        averror_as_python(ret, __LINE__); goto cleanup;
+    }
+
+ok:
+    r = Py_True;
+
+cleanup:
+    av_packet_free(&output_packet);
+    return r;
+}
+
+
+static PyObject*
+load_encode_and_write(AVAudioFifo *fifo, AVFormatContext *output_format_context, AVCodecContext *output_codec_context, int64_t *pts) {
+    const int frame_size = FFMIN(av_audio_fifo_size(fifo), output_codec_context->frame_size);
+    PyObject *r = NULL;
+    bool data_written = false;
+    AVFrame *output_frame = av_frame_alloc();
+    if (!output_frame) return PyErr_NoMemory();
+    output_frame->nb_samples     = frame_size;
+    av_channel_layout_copy(&output_frame->ch_layout, &output_codec_context->ch_layout);
+    output_frame->format         = output_codec_context->sample_fmt;
+    output_frame->sample_rate    = output_codec_context->sample_rate;
+    int ret = av_frame_get_buffer(output_frame, 0);
+    if (ret < 0) { averror_as_python(ret, __LINE__); goto cleanup; }
+    if (av_audio_fifo_read(fifo, (void **)output_frame->data, frame_size) < frame_size) {
+        PyErr_SetString(PyExc_Exception, "could not read audio data from AVAudioFifo"); goto cleanup;
+    }
+    if (!encode_audio_frame(output_frame, output_format_context, output_codec_context, &data_written, pts)) goto cleanup;
+    r = Py_True;
+
+cleanup:
+    if (output_frame) av_frame_free(&output_frame);
+    return r;
+}
+
+
+static PyObject*
+transcode_loop(Transcoder *t) {
+    AVCodecContext *output_codec_context = t->enc_ctx;
+    while(true) {
+        const int output_frame_size = output_codec_context->frame_size;
+        bool finished = false;
+        while (!finished && av_audio_fifo_size(t->fifo) < output_frame_size) {
+            if (!read_decode_convert_and_store(t, &finished)) return NULL;
+        }
+        while (av_audio_fifo_size(t->fifo) >= output_frame_size || (finished && av_audio_fifo_size(t->fifo) > 0)) {
+            if (!load_encode_and_write(t->fifo, t->ofmt_ctx, t->enc_ctx, &t->pts)) return NULL;
+        }
+        if (finished) {
+             bool data_written = false;
+             /* Flush the encoder as it may have delayed frames. */
+             do {
+                 if (!encode_audio_frame(NULL, t->ofmt_ctx, t->enc_ctx, &data_written, &t->pts)) return NULL;
+             } while (data_written);
+             break;
+         }
+    }
+    return Py_True;
+}
+
+static PyObject*
+transcode_single_audio_stream(PyObject *self, PyObject *args, PyObject *kw) {
+    static char *kwds[] = {"read_input", "seek_in_input", "write_output", "seek_in_output", "output_bitrate", "container_format", "output_codec_name", NULL};
+    Transcoder t = {.container_format = "mp4", .output_codec_name = ""};
+    if (!PyArg_ParseTupleAndKeywords(args, kw, "OOOO|Iss", kwds, &t.read_input, &t.seek_in_input, &t.write_output, &t.seek_in_output, &t.output_bitrate, &t.container_format, &t.output_codec_name)) return NULL;
+    if (!PyCallable_Check(t.read_input)) { PyErr_SetString(PyExc_TypeError, "read_input must be callable"); return NULL; }
+    if (!PyCallable_Check(t.seek_in_input)) { PyErr_SetString(PyExc_TypeError, "seek_in_input must be callable"); return NULL; }
+    if (!PyCallable_Check(t.write_output)) { PyErr_SetString(PyExc_TypeError, "write_output must be callable"); return NULL; }
+    if (!PyCallable_Check(t.seek_in_output)) { PyErr_SetString(PyExc_TypeError, "seek_in_output must be callable"); return NULL; }
+
+    if (!open_input_file(&t)) goto cleanup;
+    if (!open_output_file(&t)) goto cleanup;
+    if (!(t.fifo = av_audio_fifo_alloc(t.enc_ctx->sample_fmt, t.enc_ctx->ch_layout.nb_channels, 1))) {
+        PyErr_NoMemory(); goto cleanup;
+    }
+    int ret;
+    if ((ret = swr_alloc_set_opts2(&t.resample_ctx,
+        &t.enc_ctx->ch_layout, t.enc_ctx->sample_fmt, t.enc_ctx->sample_rate,
+        &t.dec_ctx->ch_layout, t.dec_ctx->sample_fmt, t.dec_ctx->sample_rate,
+        0, NULL)) < 0) { averror_as_python(ret, __LINE__); goto cleanup; }
+    if ((ret = swr_init(t.resample_ctx)) < 0) { averror_as_python(ret, __LINE__); goto cleanup; }
+
+    if ((ret = avformat_write_header(t.ofmt_ctx, NULL)) < 0) { averror_as_python(ret, __LINE__); goto cleanup; }
+    if (!transcode_loop(&t)) goto cleanup;
+    if ((ret = av_write_trailer(t.ofmt_ctx)) < 0) { averror_as_python(ret, __LINE__); goto cleanup; }
+
+cleanup:
+    if (t.fifo) { av_audio_fifo_free(t.fifo); t.fifo = NULL; }
+    if (t.enc_ctx) avcodec_free_context(&t.enc_ctx);
+    if (t.dec_ctx) avcodec_free_context(&t.dec_ctx);
+    if (t.ifmt_ctx) { avio_closep(&t.ifmt_ctx->pb); avformat_close_input(&t.ifmt_ctx); }
+    if (t.ofmt_ctx) { avio_closep(&t.ofmt_ctx->pb); avformat_free_context(t.ofmt_ctx); }
+    if (t.input_ctx) { av_freep(&t.input_ctx->buffer); avio_context_free(&t.input_ctx); }
+    if (t.output_ctx) { av_freep(&t.output_ctx->buffer); avio_context_free(&t.output_ctx); }
+    if (t.resample_ctx) swr_free(&t.resample_ctx);
+    if (PyErr_Occurred()) return NULL;
+    Py_RETURN_NONE;
+}
+
 // resample_raw_audio_16bit {{{
 static PyObject*
 resample_raw_audio_16bit(PyObject *self, PyObject *args) {
@@ -132,6 +474,9 @@ CALIBRE_MODINIT_FUNC PyInit_ffmpeg(void) {
         {"resample_raw_audio_16bit", (PyCFunction)resample_raw_audio_16bit, METH_VARARGS,
         "resample_raw_audio(input_data, input_sample_rate, output_sample_rate, input_num_channels=1, output_num_channels=1) -> Return resampled raw audio data."
         },
+        {"transcode_single_audio_stream", (PyCFunction)transcode_single_audio_stream, METH_VARARGS | METH_KEYWORDS,
+        "transcode_single_audio_stream() -> Transcode an input file containing a single audio stream to an output file in the specified format."
+        },
         {"wav_header_for_pcm_data", (PyCFunction)wav_header_for_pcm_data, METH_VARARGS,
         "wav_header_for_pcm_data(audio_data_size=0, sample_rate=22050, num_channels=1) -> WAV header for specified amount of PCM data as bytestring"
         },